I see a few projectors using metal enclosures and all. Where do you get your metal supplies from? The local home depot only seems to carry real thin stuff. Or am I going overboards and MDF is perfectly fine? I worry about heat resistance and burning down the house.
It all depends no where you live. You're in New Jersey according to your location info so you should be able to find a local metal market with good prices. I personally get my metal from Online Metals, but I only live a few miles from them so I can do local pickup.
Edit: forgot to mention, they don't charge cutting fees which is really nice. Also they only guarentee their cuts to + or - 1/8" so make sure you keep that in mind.
I think I can make a generalization here and say that, if you don't know where to look for sheet metal other than Home Depot, you probably face a long and painful experience and poor results trying to do metalworking. Go ahead and build an MDF enclosure that follows the concepts of most DIY projectors. It won't burn up, just keep the light from contacting any wood.
You'll end up with better results and no trips to the hospital, those fresh sheet metal edges can be really nasty if you don't know what you're doing.
I agree with cbm5 about metalworking - it's a lot harder than woodworking without the right tools and knowhow. Having said that, though, what better way to learn than to shed a little blood and screw up a project or two?
Now, onto an answer: Aircraft Spruce has sheet metal in all sorts of thicknesses and reasonable prices (compared to Home Depot, it's a steal). 0.040 2024-O or (even better) 0.050 2024-T3 would be strong enough to hold projector parts together and are both extremely lightweight (compared to sheet zinc or steel, and especially to MDF).
Final disclaimer: aluminum splinters are no fun so watch those edges