Time to Die

Designing and 3D printing (in metal!) some gaming dice! Mainly as a way to familiarise myself with the processes and pitfalls of metal 3D printing.

Since I need to get my head around 3D printing in metal, and one of the classes I tech-support at work is a board-game-design class, I felt this would be useful on multiple fronts. Since there is no real point in custom 3D printing something that I can buy much cheaper mass-produced off the internet, I went for something genuinely unique too: My die are 8-sided and numbered zero (blank face) to seven, and in pairs, so you can roll 00-77 in octal (0-63 decimal equivalent). I rather like base-8 numerics, and my modified-octahedron came out both aestetically and dimensionally pleasing to me, and also 7 dots can be arranged in a way that is likewise aesthetically pleasing plus seems to bypass the normal human subitizing (sight-counting) limit.

I first generated an octahedron in Blender, chopped of the 'top' and 'bottom' points for aesthetic reasons, and generally smoothed out the edges with a bevel filter. Next I generated a bunch of cylinders to subtract out of that mesh, generating the below 3D model (coloured for clarity).

8-sided die.

Tetrahedrons are actually symetrical on all axis, but I found clipping back two of the points had a nice aesthetic, let the whole thing fit snugly inside an invisible cube (bounding box) with the truncated height the same as the width on the non-truncated side edges. I also found a further use for the flattened points: as I intended to use two die together to form a two-digit pair, I needed to mark one of the die to indicate it was the first digit of the pair. I cut out a circle on the top and bottom of one of the die, in the truncated bit, to be this indicator:

High and Low die.

So now you roll both die and take the marked one as the upper digit and the unmarked one as the lower digit for an octal result of 00 to 77.

I am also quite happy with how the hexagonal pattern of dots came out. I also tried some other ways of arranging the dots, such as a more traditional 2x4 grid, but found it was very difficult to tell at-a-glance what the number is. The hexagonal arrangement seems to bypass the numeric part of the brain and instead tap into the linguistic center, treating the various patterns as glyphs to be read rather than numbers to be counted (completely non-expert hypothesis). Also the hexagons fit quite nicely into the equilateral-triangle-based faces of the octahedron. I shy away from using numeric digit glyphs (and likewise specific languages and alphabets) as I like to keep things culturally neutral and universally applicable when I can.

And here are the STL files for these two die. I printed mine at 21.3mm high: 1/64th bigger than I wanted so I had a bit of room to sand-and-polish them back from the raw print output. You can print them at what ever size you like and your equimpent can handle. Tip: Use 100% infill as the mass (and center-of-mass) of them is important for them to roll well (for metal printing you need 100% infill anyway due to the way the process works).

8-sided die with Hindu Arabic glyphs.

Above: What they might look like using familiar Hindu-Arabic numeric glyphs. Note that this level of detail is too fine to 3D-print in Stainless Steel, or on a consumer-grade filament printer, though a resin printer should handle it fine.

 

I did consider doing a test 3D-print in PLA plastic, but only have easy access to a filament printer with a resolution too chunky to make this relatively-detailed item at present (a resin printer is on our maker-space budget-approval list). Instead I went strait to a 3D printing house that can do metals. I chose stainless steel, which was a little more expensive than aluminium, mainly because I found a chemical 'blackening' process for that metal which has some interesting potential which I will discuss below.

I had my first run of metal printing done by Zeal 3D Manufacturing Services in Melbourne, Australia (mainly because they were the first to get back to me with a quote). They were very helpful (and patient!) with assisting me get my model into a form that had a decent change of printing well - I am pushing hard on the resolution limits for that particular material! Print time from model-confirmation-and-payment to arrival-in-the-post was about 2-3 weeks as a standard-priority job.

TAEM Students note: If you are interested in going this route, I recomend bringing your 3D print files to me first so I can pre-check them before you submit them: I can likely save you, and your 3D print supplier, a bit of back-and-forth resolving issues - Stainless Steel printing is not super-high detail, other metals or plastics may vary in other ways: I am gradually trialling different materials and print processes to develop my knowledge in this area so I can advise students in this regard.

Also note that this isn't at all cheap: Even something as small as these two dice, you are looking at around $20 in plastic or up to $100 in metal (so I won't be setting up an Etsy store any time soon!). That cost was one I was willing to bare in this case as it produced some really nice results and was also a learning task in itself. YMMV, and a quick-and-nasty low-res print on our own in-house consumer-grade printers may be more appropriate, at least for prototyping! And keep the potential costs in mind before approaching a 3D print manufacturer, since I'm sure they already get plenty of glassy-eyed hopefuls that balk as soon as they get the production quote! (I suspect all the printers I am trialling are most surprised that I actually do generally follow through on the quotes they send me!)

After some back-and-forth with the printer to get my model within spec. for their printing process (my origional design had the holes a bit too close together and not deep enough to print well for this material), I got 4 dice pairs printed. At around $90 per pair, that wasn't cheap, but not a bank-breaker either. For comparison, a high-res plastic print would have been about $20 per pair, and aluminium would have set me back about $70 per pair (for which I would have to anodyse them if I wanted to colour them in a way that wouldn't easily wear off, so the small extra expense was probably worth saving me the trouble of doing that in a small-lab setup).

They came back from the 3D printer already quite usable without further embelishment:

Rough-printed Die as they arrived in the post.

Next, lets try some chemical processing, and plain old painting:

First pair, I lightly sanded their surfaces back (to make sure the surface was fully exposed to the chemicals I was about to apply) then dunked them in Caswell Stainless Steel Blackener for a few minutes, then washed the chemical off as per instructions. Then, one face per hour (so the paint wouldn't run as I turned the dice over), three times over, I hand-painted in the dots in a nice bright red modeling-paint:

Chemically-blackened shell, hand-painted dots.

Here, I used a wax crayon to in-fill the holes, and then dunked the die in a pot of stainless steel blackener. This chemically reacts with the surface of the stainless steel and blackens it to a small depth into the actual metal, so it won't wear off like paint would. Sice die get regularly handled and tossed about, that is important!

Chemical blackening process.

After washing the blackening chemical off the die, the wax was cleaned out of the holes. As the wax protected the insides of the holes from the blackening chemical, the holes remained a nice bright silver.

Chemically-blackened surface, dots left 'bright'.

Conversely, I also tried using a fine brush to apply the stainless steel blackener inside the dots with the outside left alone, washing it back out after about 3 minutes chemical-reaction-time as per instructions. I used a rotary engraver to remove the oxide layer from the metal inside the holes for the blackener to take properly, and then I had to sand and polish the surface for better contrast since the 'black' is not as good as black paint would be. In the end, more work than painting for a not-as-good effect, but you have to try these things to find out, and while not as good, it isn't actually bad:

Blackened-dots Die.

Since I already have a blackened-die with painted dots, I will keep the chemically-blackedned-dot die for my student-demo pieces and won't be doing a bright-face+black-paint-dots version for this set. Though maybe I should paint one and leave the other like this for comparison?

 

Another day another die!

Using Amiga Engineering this time - they have a higher resolution - and proportionately more expensive - print process. I was planning to go with stainless steel again, however my job was too small to start up the machine for on its own and they didn't have any larger jobs pending in stainless at the time, so they offered to do them in titanium for a SS-price instead. My preference for stainless steel is that chemical-backening process I used above, but Amiga sent me some information on some interesting-looking heat-treating colour effects you can get with titanium, which convinced me to try it out.

While I was very happy with the print-output of my first run of dice, I made some minor changes to my model - a slight adjustment to dot size and placement as well as increasing the bevel on the sharper edges a litle bit. Amiga also suggested I round out the sharp inside-bottom edges of the dot holes to make printing a bit easier, and I suspect this will also improve paint-flow on dice I hand-paint in the dots too (in the painted sample of my die-run above, you can see how the paint tended to pool more thickly around the bottom-edges of the dots due to the sharp angle's interaction with the wet paint's surface tension. With that sharp angle gone, I might even get away with only 2-coats instead of the 4 coats I had to do to (mostly) cover the inside-corner paint-pooling effect above!

Charm-Bead Model.

For this version, I also 'cored' the model with a 2.5mm tunnel through from top to bottom: I already had a bunch of nice playing dice, so wanted to do something different for this run. So I am printing them at 50% size (so 10.5mm bounding box) and with the mentioned hole vertically through the middle. I also didn't make two-digit variations this time, just one dice model. While these can still be used perfectly-well as dice like this, these are intended to be dice-themed jewelery beads for a charm bracelet, necklace or similar.

Charm-bracelet Die.

Next up, I will (when I find time - it is presently start-of-teaching-session madness at work!) try some of the heat-tempering colouration suggested by the print supplier. Will update here when I get some pics.

 


 

If we ever get our resin-printer here (sigh), I am also planning to run off some plastic versions of these beads as part of my self-training on that equipment, then see what I can do (and document, of course!) with those too. (If I was just doing it for myself, I would eat the few dozen bucks and get them commercialy printed, but holding off on plastic prints in order to learn to do it on our planned in-house gear is kind of part of my job!)

Aluminium is another material I am interesting in doing some time - I specifially want to see if I can build some sort of (shoebox-sized) small-lab anodysing setup - I'll probably try to make that and test it on some scrap metal before ordering the prints, though.

 


 

I managed to get the filament printer at work going again (I needed to make a replacement part by combining replacement parts from the MkII and MkIII versions - our MkI is 4 years old, so of course you can't get any parts, or a word out of the manufacturer - welcome to 21st Century Human Technology!

Here are some prints:

Bad 3D prints.

Top is a fairly normal result when the print detaches from the print bed and gets dragged around melted onto the print nozzle. That is mainly down to my inexperience in setting up a sufficient bed-adhesion layer. Bottom is the normal result when web designers who think being able to copy-paste some Javascript qualifies them to call themselves 'programmers' - more specificaly, the spacing of the 'rifts' at 2.5mm, 5mm, 10mm (and I am sure 20mm, 40mm... if we went on) indicates a stupidly sub-novice screw-up in the handling of float-int conversion... we can also extropolate from this that the driver is working in centimeters as its base unit.... Anyway....

Below is the successful fresh-off-the-printer filament print. Done in black ABS plastic just because that was what happened to be spooled on the printer when I got it working again. It will actually look a bit better (though I doubt good) once I get the printing-supports off and give it a light sanding and polishing). Maybe it is just that ABS plastic is not the best material for this job... I will have to try a PLA print some time.

Good 3D print.

With ample application of supports and rafts, (and trying 3 different 3D print slicers, all of which appear to be inscestuiously copy-pasted from each other to differing degrees of failure-to-function, sharing a general UI that also makes me question the developers' wannabe-programmer-web-designers' design credentials!)... it is actually possible to get a passable 3D print out of a consumer-grade filament printer. And to be fair (though only on the hardware, not the reprehensible software!)... above, I am deliberately pushing the limits of what is really a rich-kids'-toy technology, mainly to show how far it can, and cannot, be pushed. There certainly are valid uses for this print technology, though:

Actually useful 3D print.

Above: A more appropriate job for this type of 3D printing technology: larger, lower-detail items are good. The insert trays were what I printed: the outside of the case was some sort of nifty-looking component box I bought several of online from a warehouse clearance sale some years ago and have been finding uses for ever since. I soaked it in near-boiling water to soften the glue, then gently pried out the component tray inserts that came with it, using them as a measurement guide for sizing the die-holder inserts I printed to replace them. Black ABS plastic again, as that was already loaded in the printer, and I thought it would look best anyway.

Actually useful 3D print.

Above:The label on the front was done in an office label-writer and carefully trimmed to fit an existing cavity on the top of the case.

....and for crude prototypes. But if I had an actual lithograpic resin printer right now, I would probably use that for all those too!

Consumer 3D-printer software is universally bad - really bad, even for 21st century cloud-ware junk - is what I am saying. It's current state of existence is an actual insult to the very concept of both computers and human inteligence, though, since we keep accepting it in that state, the latter may be rightly deserved. If only someone in the industry actually cared enough about their own products to invest in coupling them with decent software drivers/programs... and supporting them for longer than a meth-addict's attention span. Messing around for the better part of the day to get a slicer set up to output something intelegable to the printer, and having to shuffle stuff about on SD cards because connecting to a printer with a USB cable isn't good enough for modern in-the-cloud consumer 3D-print software, is totally unacceptable, and is actually just a great way to make me really wish the windows in my office could be opened so I could toss the poorly-supported junk out of one!

And, no, I really don't want to subscribe to your pointless adver-zine and honestly resent having to sign up to your tediously under-resourced 'cloud' 'service' just for the privelege of downloading drivers/extensions. I will save the advertisers you sell my personal information to some CPU cycles on their profiling/analysis tools: I am in the RAGING MAD CONSUMER demographic!

Note I am not calling out particular brands here (I even doctored some images to remove visible branding on device parts) as, so far, my depressingly bad experience with this technology is universal, and my very limited faith in humanity leaves me doubtful that I have much chance of encountering an exception. If I do, I will certainly name the good ones. And shout their praises from the roof of my office building, quite possibly! I find modern computer software (and many web sites too) in general irk me in their facile exessively-featured-at-the-expense-of-actual-function anti-user uselessness, and 3D-print software takes pole position (though some of the business back-end interfacing at my workplace is a serious threat to that position!).

 

Anyway...

Bonus: 3D printing, particularly at professional quality, is fiddly and expensive. As a much cheaper and simpler approach, particularly good at the game-design prototyping stage, doing something by hand may be more effective: Here I used a rotary hand engraver to crudely make my die set out of octahedral blanks I bought for a few dollars online (other common die shapes such as D4, D6, D10, D12, D20 also available). You could even just write-on the faces with a permonant marker, but by engraving in the holes, and then colouring in those holes with a sharpie I get something a bit more wear-resistant. This one was done at home during COVID lockdown, so is a bit rough: with a small drill press and an X-Y-adjustable bed-clamp, I could do a much neater job with the holes properly aligned, but even this crude job is a good example for if you just want to quickly make up some custom die for play-testing an idea.

Hand-engraved die.

More to come: Hopefully we will be getting a laser cutter/engraver in our maker space soon, and I intend also making a set of trays that will let me do more elaborate die-face graphics onto such plastic blanks off a template that students can use to design their own faces into.

 

So... what to do with a pair of 8-sided die that count 0-7 each or 00-77 together? Well, a tabletop-role-playing-game is an obvious use! You could simply modify one of the open-source "D100" systems, which use two 10-sided die to roll 00-99 in decimal, to instead use 00-77 in octal (base-8), for example.

Of course I made one .... But it is a very rough early draft with many bits still missing and completely un-play-tested, so I haven't released it just yet! - I didn't follow my own advice and modify an existing D100 system and instead worked it up from scratch, so it is really badly play-balanced right now! Stay tuned, I will slowly pick at it and improve it as my interest and free time allows. Note that while the game plays in octal, this is largely hidden from players, as long as they know their (decimal) 8-times tables up to 7x8 players may not even notice!

 

Notes on Dice Design.

Formally, The singular is dice and the plural is die. This gets really confusing and I have undoubtedly messed it up multiple times in this document too! I don't think it really matters - I take the view that any use of language that remains clear in meaning is correct usage. When I talk about resin-casting dice, I deliberately use dice as both singuular and plural, to differentiate it from the casting-die, which is the mould into which the resin is poured!

There is a convention to the way numbers are put on faces of a dice. That convention is that all opposing faces should add up to the same number. So for a standard 6-sided dice, the opposing faces are 1:6 2:5 3:4, all adding to 7. On my 8-sided die, the opposing faces are 0:7 1:6 2:5 3:4, also all adding up to 7 (because I am counting from zero... both happening to add to 7 is coincidence: nothing special about the number 7 here!). On a 20-sided dice, 1:20 2:19 3:18 etc. all adding to 21. For dice without opposing faces, such as tetrahedrons or some of the wacky odd-number-faced die from my sample bag, this system is out the window and you probably should just do your best to disperse the numbers around as far from each other as possible.

For non-numeric dice, there are no real rules, but you probably should again think about what may constitute an 'opposite' in the context of your game and go with that. One example is 'fateā„¢' or 'fudge' dice which are 6-sided dice configured effectively as 3-sided dice, as there are two faces with a + symbol, two with a - symbol and two with no symbol. These dice just have the same symbol on opposing faces, so +:+ -:- blank:blank.

Fudge Die

Here is a bunch of other non-numeric die from my demo/sample collection:

Random collection of non-numeric die

Top Row: constellations, planets, colours, shapes, rock-paper-scissors, I-Ching, seafood (actually, from a form of Mahjong, I believe).
Bottom Row: emotes, weather, direction, terrain, dungeon-interor, furniature, treasure (some of these might be used for on-the-fly random map generation in what is often called a Westmarch game). A numeric die and a look-up table can do the same thing, but specialist die can be fun in their own right!

Shape is also important: Below are two different designs of 16-sided dice. The left one has sides of slightly different shape and angle between faces, which means it is not going to be truly 'fair' (though it will be close enough for most purposes). The right dice uses an octagonal trapezohedron design (as per the pentagonal trapezohedron used for TTRPG 10-sided dice) and is far better for ensuring reliable randomness, at the cost of sharp angles that make the physical roll a little awkward. Two types of 16-sided dice.

100-sided die have the same issue. I did get one amongst the two multi-die sets I purchased to get my big variety of numeric-die samples, but I removed it from my collection because it was big, stupid and I don't care much for numeric base-10 anyway! I wouldn't make myself a 64-sided dice for the (first two) same reasons, and my dual-8 die set performs exactly the same function anyway.

The platonic solids are obvious good choices for dice shape as they are very regular, providing 4,6,8,12 and 20 sides identical in size, shape and angles between. There are a number of other semi-regular shapes with identicaly-shaped sides though the faces themselves are not regular, and the angles between them differ, though in consistent ways, so the die can probably still be considered 'fair'. These are usually constructed by further triange-dividing the faces of the platonic solids, providing face counts such as 12, 24, 24, 30 and 60 (repeats there are deliberate - there are multiple ways to get some of those side counts).

A bunch of various-sided die.

The 4-sided dice is an interesting one to consider separately too, as the tetrahedron (below, left) is often used but rolls really poorly due to its sharp angles and low center-of-mass:

Three styles of 4-sided dice.

Above center is a tetrahedron with the corners rounded off for better roll, which also gives you an up-facing surface to put the numbers on. And above right is an entirely different approach to a 4-sided dice. ... you could also make a D4 by doubling up numbers on a D8 (or trippling on a D12, quintupling on a D20!)

Two slightly different D8s.

Similarly, above are two D8s. Left is the more conventional sharp octahedron, and right is one with rounded corners (I got this one after I had shaved the tops off my own D8 design. After getting this die, I played around with taking off my edge corners, but because my dot pattern only has two-axis symetry on some faces, and shaving all the corners lends itself to three-axis symetry, I decided to stick with dice with a definite 'top/bottom'. A purely personal-aesthetic decision).

Collection of odd die.

Above are some assorted 'weird' die, (yes, I consider D10s 'weird'). The D10's, being pentagonal trapezohedron in shape, are 'fair' (if a little pointy) as is the D3 made from a D6 with numbers I II and III doubled-up on opposite sides. The D7, D5 and D16 are not strictly 'fair' for reasons discussed above, but are close enough for just having fun with! A truly 'fair' D5 couid be made by quadrupling-up numbers on a D20. You could also make a 'rounder' D10 by doubling up numbers on a D20. The only way to get a 'fair' D7 would be to double up numbers on a 14-sided septagonal trapezohedron, though.

 

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