To make the Tee pen I started with a 1" x 1" x12" long piece in a wood chuck and turned it down to the diameter desired leaving the parting off till the cartridge hole is drilled.
Removing the live end I then drilled a 1/8" hole in far enough so the cartridge does not bottom when it is installed. This required a 6" drill bit.
I then drilled a 5/32" hole deep enough to accept the nib end. This hole needs to be small enough so the nib end is snug when pushed in.
I applied the finish at this point.
Then using the parting tool and skew tip I parted it off creating the recessed area for the ball during it.
Make sure to measure your cartridge before drilling the holes.