Circa late 60's early 70's, the idea of the Mattel thingmaker.
The molds as I recall were clear plastic, the "goo" was I believe latex has it had already got hard in the bottle by the late 70's when I had one, no heat was used that I recall
Mine the molds were for a soccer player, with ball, the goo was flesh colored, it came with wire skeletons to make the figures bendies,
You didn't paint but rather used rub off decals,
I am trying to recall the name of this toy,
Many thanks,
Cheers,
P.