We saw these at the fair and thought, "Hey, we have a boat load of old records, here is a project so they will take up even more room." Actually, these are pretty cool.
Heat the oven to 400 degrees. Making these after pizza is very convenient. Find a bowl that is the big enough that the sides of the record won't hit the baking sheet. Put the record so it is centered on the bowl and pop it in the oven.
These melt quite quickly so don't walk away. They don't smell so great either.
If you don't like the way it fell when melting you can reshape it. If it gets to hard just put it back in the oven to make it pliable again.
To make a tall bowl we used a quart Mason jar. The record label just happened to be the same size as the bottom of the jar.