Gridfinity 3x2x3 no-lip holder for 2 countersink bits and 6 hex keys (allen keys). 

In the photo I'm showing the Parkside countersink bits available in Germany and elsewhere from Lidl and co. However, most other similar bits should fit. If you're unsure, download the model, and use your slicer to cut away most of the model leaving only the top 2-3mm. That should leave you with a slim piece of plastic with the cut-out shape in it. With that you can test the fit of the cut-outs to your specific bits / tools.

Specifically, the inserts are designed for:

• Countersink quarter-inch bit with the drill bit inserted
• Countersink quarter-inch bit without the drill bit
• 6x Hex (Allenkey) holders 20mm deep for allen keys:
  • 2mm
  • 2.5mm
  • 3.mm
  • 4mm
  • 5mm
  • 6mm