Remember the “Thingmaker” in the sixties? It was a hot plate that cured smelly liquid plastic in molds that made bugs and such. I wonder how many houses burned down from those. I remember leaving mine on and accidentally stepping on it in the dark and burning the $h!+ out of my foot.
I had one of those also! First time I’ve thought of that toy in a long time.
Also had a chemistry set from sears. Do they still make those?
I remember a thing Mattel had called “The Strange Change Machine’’ that did just what you said. I think it was Christmas ‘69.