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I need a step by step guide on how to make plastic in order to house my projects. Have searched the web, all i find is how to make plastic from milk. I need to make real plastic so please help with your idea. Thanks
What I do is a tad expensive if you can't find small bits of what you need, or want to make several boxes, but I like it, its result is very tough and it's very easy to do, and the bits are reusable. You can make the exact box dimensions you want this way.
I buy acetal plastic (usually black but it comes in many colours), between 2 and 10 mm thick depending what I'm doing. It cuts and drills easily, and THREADS easily too, that's what makes it so nice to use. For a tiny box like a GPS logger I'm making, I use 3 mm thick sides, 2 mm ceiling and floor panels, and 6 mm bulkheads on each end. M2 machine screws self-tap very neatly into a 1.8 mm holes on the sides of the bulkhead pieces. I built a small show laser once using 10mm panels and M4 screws into thread made with a fluteless tap into 3.8 mm holes, and I think even at that size they would self-tap saving the cost of special taps and other tooling. Drill bits are cheap. That case dropped a metre onto concrete at one point (thin hard carpet on it though) and I couldn't identify a point of impact, there was literally no sign of it, and no damage to optics or other parts, despite the thing weighing several kilos. It would have broken a person's foot if it landed on one, but it showed no sign of impact at all. I mean I spent some time with a bright light trying to find it because I wanted to know, and there was no scratch that wasn't there already and no dents at all.
Or you could just buy the cheapest plastic or extruded or diecast aluminium box you can find, but it will still cost more if it's any good, and you'll always be compromising. With a few stainless steel machine screws and some acetal panels cut on a bandsaw, you won't have to, and that plastic is about as tough as aluminium anyway.
Acetal is resistant to most chemicals too so it's ideal for a lot of stuff, but there are two weaknesses, one is its resistance is so extreme it's very hard to glue, so don't try. Screw it together like metal or wood. The other is it has one chemical weakness. It is degraded if it comes into repeated contact with chlorine or its compounds. So you wouldn't use it at sea, for example..
Custom case? Then you will need to do what I did, unless you can find a plastic moulder who will make what you want. Unless you are making thousands of them for profit, my way is cheaper. By far. The one thing to watch is that acetal is heavy, if you have to ship it from a distant country you might need to consider a lighter plastic that can take similar methods, like acrylic, which can also be easily glued with neat methods using a solvent to 'weld' it. Or polycarbonate, but that's heavier and tends to crumble after a while at fixing points if stressed hard.