Cool BB1... and as Slinter alluded to... nice exposure to 3D printing in the workshop.
8 slots... I will never advocate the adage of "you can't have enough drills", however, in spite of a quick change bits, a few dedicated ones are a blessing in disguise.... though mine are nowhere as neatly organised.
If your first cut is too short... Take the second cut from the longer end... LBD