2019-01-06: Fixed OpenSCAD file; now working with Thingiverse Customizer (removed non-standard characters). Corrected some typos.
This is a space efficient, customizable holder for tool bits such as those used by Proxxon or Dremel multitools. The holes are arranged in a hexagonal pattern for high storage density. Up to three different hole types with individual diameter and insertion depth can be defined. This enables combined storage of different shaft diameters, as well as the possibility to place less frequently used tools at a lower plane, hence larger tools (like cutting wheels) are kind of 'stacked' on top of each other (see photos). Two of the three hole types ('type 1' and 'type 2') can be indicated by marker pits such that different depths can be easily recognized prior to bit insertion (no trial-and-error necessary).
For some reason my OpenSCAD designs tend not to work reliably with Makerbot's customizer on Thingiverse, so I recommend using OpenSCAD's built-in customizer. It has the advantage that parameter sets can be easily stored in a '.json' file, and later recalled on demand. A few configurations are included in the provided .json file, and as .stl files.
Simply copy the .scad and .json files into the same folder, open the .scad file and launch the customizer: check Edit -> Preferences -> Features -> customizer (you may need to scroll down), then uncheck View -> Hide Customizer). Note that at least a 2018.x version of OpenSCAD is required: on the download page (http://www.openscad.org/downloads.html) scroll down to Development Snapshots and download the newest version.
Printing is straight-forward, no support needed, infill of 10% is enough.