Why print many drill bit holders when you can print one that potentially exceeds your needs?

13x13 bit grid on a 3x3x2 gridfinity bin will allow you to store 169 6mm bits with an 8mm cavity.

DISCLAIMER: it may be printer configuration specific, but my print came out snug in some holes, friction/press fit and I will have to fight them a little bit to get them out to use, your mileage may very

If you are not interested in a friction/press fit and would like greater tolerances / more space between bits, see my looser fit variant at: https://www.printables.com/model/371102-gridfinity-121-6mm-bit-3x3x2