While I get what you're going for that's really not the best analogy.How hot does the oven get? How hot does the light get?
Worst case scenario is that they burn a little and don't look as sharp. It would be hard to make the pie tin melt or do anything dangerous.
Are they going to be on for the entire show? Throwing in a couple of cooling periods might help - example: At my high school, I had my dad laser-etch a thin sheet of aluminum with the school's logo (he's a tool and die maker.) The gobos worked well, but after about 15 min they started to burn. They were ok as long as the light was not shaken/moved/adjusted, then the brittle aluminum broke. Of course, it didn't help that he forgot to clean off the oils from the machining process...Guys--
They will be used for one 2 hour show (okay we'll say 3 hrs to be safe).
I bake cupcakes in my Source Fours all the time...I've never thought of comparing the lights to an oven before... Makes a lot of sense.
A very important question.Are they going to be on for the entire show?
Great advice. This is how pie plate gobos SHOULD work.For what it's worth....
I did a show recently that used about a dozen foil pan gobos. Rarely were all on at once, most would be up for 5-10 minutes at a time, usually at 100%. All were in Source-4's at 575w, pointed straight down. Show ran 8 shows a week for 2 months. When I took them out they were like new, you'd never know they'd been anywhere but sitting on my desk the whole time.
Similarly, a couple years back I had a set of 6 foil pan gobos which were very titchy shapes; they were in Source-4's, again at 575w, focused horizontally. These ran fairly steadily for about 30 minutes each before getting to cool, in the 65-85% range. 8 shows a week for about 2 months. And again, at the end of the run, no burning, no curling, no nothing.
Get the heavy aluminum cookie sheets, thick like foil turkey roasting pans are made from.