First I stuck a bit of wood cut to size inside the pot to support it during drilling (I also used an offcut of the same piece and a rather large hammer to slightly flatten the areas where the holes were to go
).
The main problem during drilling was my crappy drill kept stalling at the slow cutting speed.
The hole cutters were fine, though.
The tap hole after ragging:
The tap sticks out further than I would have liked:
Looks nice and shiny though!!
).
