I have an old Kodak beaker, one of the thick glass pint sized ones, that i always use for proofing yeast when I make bread.

I also have used a Merz processor (tempered cabinet) for making yogurt. Believe me, I cleaned it extremely well prior to doing this. Since nobody seems to want the old Merz S2, I am thinking that I'll remove the agitation parts and use it as a primary fermenter for small batches of red wine, which does best at 85F. It seems to me that if you have the ability to control temperature to +/- 1/4, it isn't real smart to let that capability go.

I've used the black plastic trays, curved at the ends, that Home Despot sells for mixing concrete as large print trays and also have used suitcase shells for a wash tray for a tray siphon.

This probably doesn't quite fit the spirit of the original question, but then, might be interesting to someone. Once, eating in a restaurant, a partial eclipse of the sun occurred. I asked the kitchen for a box and a piece of foil, and made a topless pinhole camera. Everyone there got to see the eclipse, albeit upside down.

I suspect that I could come up with a bunch of stuff like this. For many years, there was no separation between photography and "life", so whatever there was got used for whatever was needed at the time. It's a bit different now, but who knows what's next?