As a gluten-free baker, I have to use some odd things to make items. Gluten-free dough is softer and doesn't have the structure to maintain form well on its own. For hamburger buns, I use 4" round pans that have a removable bottom and are about 2.5 inches deep. Not even sure where I found them originally.
My current conundrum is hot dog buns. Commerical hot dog bun pans are not deep enough - so the bun flattens instead of rising in height. People have tried everything from reshaping lightweight round metal circles into rectangles (what I currently use) to twinkie pans (which are too short, but do provide the height support.
A few days ago I thought of the top to a butter dish - might be about perfect. But, this is harder than I thought. Little things on the lids prevent them from laying flat (it is being used upside down, after all).
My current flash of (potential) brilliance is . . . hot dog trays or baking cups - rectangular. But, I don't know if baking cups even come in an appropriate size nor if they make heavy-duty hot dog trays that would stay supportive. I might be able to use light or medium weight, just maybe. I could pipe the dough into the tray and then put them in a pan with sides. Given that the pan is close to exactly the width of the trays (3 or 4 of them, I imagine), they won't be able to spread and the buns won't be able to flatten.
I know some of you have access to commercial items. And some of you are just plain brilliantly creative. Or both

. Have you seen anything else that might work? Where might I get a sample of hot dog trays - maybe I should just ask at a local hot dog place and see if they will give or sell me about ten of them - just to practice.