First off, my thanks to @davidaspitzer and @marmak3261 for sharing the details for doing this. This is a process I was intrigued to try out… called a slump bowl…….which is actually quite ugly sounding. I made a circle design and used Glowria to cut it out of 1/4” thick glass-green acrylic. Centered it over the upturned bottom of a ceramic coffee mug without a handle, then set it on a cookie sheet, put it into the preheated grill on our deck… at about 300-325 and let it be for about 30 min, checking in on it every 10 min. After 30 min, I inverted a small stainless steel bowl over it and very slowly and carefully pushed it down to make the sides fold downward. I left that bowl on it until it was cooled off.
It’s about 4.25” across. Not flat on the bottom because of the bowl I used to put over the top to form it. There are some imperfections, but I think it turned out really cute and fun. It’s deformed in several places, so I will call it a 'deformation rocker bowl’ or maybe a ‘roly poly bowly’ instead of a slump bowl. So, while it is imperfect, it points to other possibilities.