Step 1: Material Basics
Corrugated cardboard, something without ink is best. Why? 'Cuz I'm carcinogenophobic. PIzza, egg rolls, and such can all go in on good ol' cardboard
But Kent, you say, what if I have something sticky!?!?
Elementary my dear Watson...
Right so how I wound up doing this is my sister bought some frozen cookie dough to celebrate having moved into our apartment. Of course we didn't have baking sheet to bake them on. Blithely ignoring the warning on the package to eat it raw, I commenced to do so. Right about the third raw cookie it occurred to me that a pizza can be re heated in it's box. I had plenty of cardboard about. But oh noes!! THe cookies will stick. I lucked out and had aluminum foil, parchment paper would work fine too. Wax and butcher, not so well.
Got your stuff? Good, NEXT STEP SUCKAH!!
Step 2: Really the Only Construction Step
Rip out a piece of foil/parchment paper that can rap around the cardboard a couple of times.
Set the cardboard on the foil and wrap it up. Flatten it, make it look prretty...
Step 3: And Bake on It
It DID smell like cardboard a bit when it was baking, but it cleared up after a bit.
I used cardboard all the way up to 450 F, seemed to do just fine. I wouldn't broil on it, but for baking you should be good.
You can do a lot with a little bit of cardboard and some imagination. I'll be trying to make a cake pan next :D