The drill bit holder contains holes for 40 drill bits with different diameters, started from 1mm, step between diameters is 0,1mm. Each hole was designed for store up to 4 drill bits with the same diameter. A source of this model you may download by the link: https://forum.freecadweb.org/viewtopic.php?f=3&t=70324&p=611626#p611626 It requires Freecad v0.20 and newest.