This was designed to hold specialized drill bits like countersinks and step bits.
There are rows for bits with 7 mm hex shanks (standard hex bit size), 7 mm round shanks, and 10 mm round shanks.
Each hole is 20 mm deep and the entire piece is angled so the bits don't fall out when it's wall-mounted (I used double sided-tape).
The author marked this model as their own original creation.