Drilling a drop pot or pot melt from a clay flower pot.
There are drill bits specifically designed for masonry or ceramic tile. The latter are your best bet but the masonry bits have worked for me as well. Read whatever instructions come with the bit or go to the manufacturers website and follow the specific directions you find there. The use of a drill press is a good idea for safety and steadiness. Use minimal pressure and take your time. Don’t forget eye protection as the density of the flower pots and presence of firing flaws in the pot make results inconsistent and pots shatter prone.
Hope this helps.
David M. Kirchoff