These are my “record bowls” which I created out of thrift-store 33 RPM records.
 
First, I paint the records on both sides, then, after they’ve cured for about 3 days, they’re heated for 2-3 minutes in a 225°F oven, until the vinyl has softened enough for them to be molded.  

They are quite hot when they come out of the oven so I wear oven mitts to form them.