The rock displeased me so I set it on fire
I finally saw my friend’s kiln! It’s a big kiln.
I took the cement mold (the wrongly shaped one) and cast it into the flames for displeasing me.
Looks like the kiln can successfully get up to 1200 degrees F! The problem is, the kiln controller can only go up to one target temperature. For the actual glass slumping, I will need a ramp/soak controller, which can let me program it to hold at a certain temperature for some amount of time then move onto another temperature. Time to scour ebay and see if I can find one…