Paint kiln wash on a large, round bowl shaped slumping mold using a paintbrush or haike brush to prepare the mold. Repeat three times. Set the mold aside to allow the kiln wash to dry overnight.
Cut a piece of large, round, clear, fusible glass using a glass cutter or circle cutter of the size needed for your mold. The cut glass should also be the size needed for your prepared mold. Cut smaller pieces of fusible glass and arrange the glass according to your design on the clear base glass.
Cover the kiln shelf of your glass fusing kiln with kiln shelf paper or fiber paper. Place the prepared glass on the covered kiln shelf.
Fire the glass in your glass fusing kiln until the glass is fully fused. The firing schedule will depend on the size of your kiln, the brand of fusible glass you use and the thickness of your glass.
Remove the glass from the kiln when the kiln returns to room temperature.
Use a drill press and a hole saw to drill a hole in the center of the glass. Select a hole saw of the size needed to attach a drain to the center of the glass.
Use a diamond files or a glass grinder to smooth the drilled hole if needed.
Place the drilled glass on the prepared slumping mold. Put the mold and the glass in the kiln.
Fire the glass a second time until the glass slumps into the mold. Again, the slumping schedule will depend on the size of your kiln, the brand of fusible glass you use and the thickness of your glass.
Remove the slumped glass from the kiln and take the glass out of the mold once the firing is complete and the kiln has returned to room temperature.