Fired in the microwave kiln.
Small glass pieces (same coe) piled on top of each other - slightly different sizes.
Fire each 'tile' separately.
Unfortunately using a microwave kiln, you are a bit limited in the sizing of pieces.
Probably the largest you can make is just a bit under 4" dia.
It is quite limiting, but you can still get some nice work done - - (maybe glue them together if you want a larger piece!)
(The top picture isn't shown as a fired piece ....... yet)
