Here's a fun* activity: watch sci-fi and see how many common plumbing fittings, plastic pallet crates, laundry baskets and food containers you can identify. Common in TV and low-budget film, but you would be surprised how much you can find in mega-budget films too (often in the less-prominent parts of scene backgrounds). Note I am not knocking this -- done well, it shows absolute brilliance on the part of the set-designers. Magic may be smoke-and-mirrors, but set-dressing is all about spraypaint-and-lighting! Here is a few good examples...
* for certain values of 'fun' only.
The first Alien movie is a good one for this - check out the devices on the walls inside the ventilation ducts! And much much more!
Such as corridor walls made half (and their floors made wholly) of red plastic shiping pallets.
Still with Alien, the highlighted stainless steel plates on the walls and ceiling in the shot below are very popular in a lot of sci-fi. They are heat-exchanger plates out of commercial air-conditioning cooling stacks. I had a dozen of these from a scrap metal merchant several years back - stainless steel sheet is hell to cut, even with an angle-grinder!, which is probably why they are usually used as-is, even though those corner holes always end up making the panels look out-of-place and just-tacked-on (well, to me, anyway - holes that go nowhere for no reason look odd - stick a spray-painted yogurt pot in them or something!).
The sequel, Aliens had a markedly higher budget, but some surprising things still show up if you look hard enough!
I once found out why a certain prop. from Blakes 7 had a metal plate just there when I came across a particular type of vacuum cleaner at the city dump that was a very good fit, right to the hole for the hose where the metal plate was on the prop. No way I would have guessed that was what the prop. was made from otherwise! The vacuum cleaner pictured isn't quite the right model - closest I could Google - but you get the idea. The up-side-down plastic drum, on the other hand... you couldn't get a closer match custom made!
Just for a change, here is my pet peev regarding what almost always looks awful: Plasma balls/plates. It is very rare that I see these things used in SciFi without looking stupid. Below is a grab from Star Trek: First Contact showing the interface where the Borg plug themselves into the collective when not wandering around Borging things. Maybe it is just me, but that plasma plate just looks like what it is -- a kitschy ornament from the 70's. Now I have nothing against plasma plates -- I have one right here on my bookshelf where the books used to be before I digitised them all. But plasma plates, plasma balls and lava lamps are just too familiar as pseudo-techy ornamentation to get away with sticking in a SciFi prop without being visually jarring.
Which isn't to say you couldn't. But you would have to be very careful of the implementation. For example, using the technique of a plasma-ball to make a long glass tube with electric sparks running down its length would look very effective in some sort of high-power generator or weapon. .... I saw a kids' SciFi many decades ago where a plasma ball was green-screened so you just saw the electric trails and not the glass ball, and that looked really good, despite it being obvious how it was done.