I have a long list and some were mentioned in the Shit I Used to Do Back in the Day thread. I'll just start with one so as not to steal the thunder of others. Creepy Crawlers - if you look at this picture you'll see the "Thing Maker" which was a souped up hot plate with no protection. The metal molds in the foreground were handled with flimsy "handles" that you squeezed to insert in the mold so you could set it in the open hot plate. After they cooked for a while you had to stick that handle back in the mold without touching the hotplate or mold (both about 500 degrees) and move it to the black tray (filled with water) to cool the metal mold down enough to touch to peel out the rubber like bugs you made (which were also a swallowing hazard). You can see from the kids on the box that it was intended for little kids.