Best I can tell there are only 2 bits that I've excluded that are only good for 2 kits that I could find information on. One of which isn't even a pen kit really and the other is for an alternative metric (12mm) bit for which an SAE bit is actually the first choice in the instructions. The letter P bit that is in there isn't really necessary as none of the kits use them. That frees up one spot anyway. I do agree that I need to keep this to what can fit in a small flat rate box. Anything larger and shipping becomes a problem. That means the largest I can go is 8 5/8" x 5 3/8" so there is some wiggle room over what is configured now. But at what point does it become too big for the bench so to speak I guess is my concern. Take a SFRB and put in a free spot on your bench and see if that's acceptable to give up that space. What I might look at doing is having 2 options. One as shown with the letter bits in place and one that omits the letter bits but offers holes to fit MT2 accessories such as your mandrel and centers. The problem I have to watch out for with that is stability of loading up heavy live centers and such to the outside of the platform. Oh and if any of the kitless guys are interested, I'm working out a kitless setup in my head. There will be a spot for a 1" die, tap, and drill bit for each of body, section, clip, and a few extra holes for feed taps.