[BrianG]

The only trouble I've seen with the folded aluminum trays is that if you get any stress cracking at the bend, that joint is weakened and can be prone to snapping.

Also, different types of aluminum are better than others. For workability, I usually use 6061-T6 from onlinemetals.com. Thicknesses around 1.5mm (~1/16") work well. I tried some 6061-T6 from Tower and it stress cracked badly no matter what I did, so I'd stay away from that stuff.

Right before bending, I usually heat up the metal to over 200*F. The bend seems to be less prone to cracking. It also helps to increase the bend radius a little. So, instead of a really sharp 90* corner, it's more like a 90* small arc. Since I use a vice and hammer to do my bending, I cut a piece of steel and rounded off the edge as the "bending plate". This makes the aluminum bend a little more gently.