Plastic Sheet?

Hi Everyone,
Looking to make a box to sit under my Prusa I3 to hold the power supplies and electronics and things.
Want to avoid using wood in case of fire so am looking for a plastic sheet I can buy easily and cheaply, that doesnt catch fire about 3-5mm thick.
Anyone have any ideas on what to use and where to get it?
Thanks
Tomas

I'm not sure of the not catch fire part, but I got a free sheet of acrylic from a local supplier as an off cut, used this for a PC case window, was I think 4mm thick, would have made a nice box, was about twice the height of a mid tower case, by about the width of a midtower pc case
sheet metal that is less than 2mm think is pretty easy to cut with a jigsaw and bend in a vise, could make a box out og 16 gauge 1.5mm sheet metal from scrap, cut, bend sand paint done

From what I've heard acrylic is expensive and difficult to cut or drill, but not sure on that

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tomas02
From what I've heard acrylic is expensive and difficult to cut or drill, but not sure on that

I have made my I3 frame from acrylic. I had it CNC'd by a friend. I did the drilling and tapping by hand though.
Any heat generated by the drill or even the tap causes the acrylic to go gummy and grab either the
drill bit or tap. It then cools and hardens and makes it difficult to remove either tool.
My advice would be to take it very slowly to prevent heat generation. If I was going to do it again I'd
try some sort of lubricant or coolant fluid.

..late response...but..

I used acrylic for the frame parts of my Mendel90.
The key to drilling the holes is making sure you have nice sharp drill bits, and properly support the underside so the bit doesn't' smash it's way out when it gets close to exiting.
I used standard HSS drill bits in a drill press on top of a wood block. Pilot drill anything over 5mm and set the drill at the correct speed for the bit.

I cut the base plate (10mm thick sheet) with a new Irwin 32T circular saw blade. I hear a collective gasp...but those Irwin blades are much thinner that your run-of-the-mill blades. If you take it too slow, it will start to melt, too fast and it will badly chip the edges. Another tip is to only have the blade set low enough to cut through to the other side. It makes the cutting angle a lot shallower.

I actually enjoy working with the stuff, and even flame polished the cut edges with a small blowtorch.

I got mine through Classique Plastics in Napier (TM dealer 'classic-plastic') as offcuts.

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tomas02
From what I've heard acrylic is expensive and difficult to cut or drill, but not sure on that

If you have a design then you can always get Ponoko to laser cut it for you. It's not cheap but it does avoid the hassle.