This holder optimizes the vertical space used versus other holders, using the minimum of 2 units of vertical space. Other holders I found were usually double or triple the height! The third photo shows how much shorter this model is versus others I've printed to store hex bits. 

This is a 1x2x2 Gridfinity hex bit holder for short/normal length hex bits. The hex holes extend all the way down to the base of the holder. Holds 38 bits securely and without wobble.

Other gridfinity models:

• Gridfinity short hex bits 1x1x2
• Gridfinity short hex bits 1x2x2
• Gridfinity long hex bits 1x2x2
• Ikea Alex Gridfinity base slim (36cm) drawer