This is a Gridfinity-compatible screwdriver bit holder for the bit-sets sold by Linus Tech Tips. One of these (1x1x25) blocks will hold exactly one set of 12 bits. They are stackable when empty. 

LTT's bits are slightly shorter than standard, but this model holds them at the perfect height. Of course, it will also work with any standard, non-LTT bits. 

While I used PETG at 0.2mm layer heights, it is an easy print and should work with most filaments/layer heights.

Note: This project is a remix of this Gridfinity block, and is in no way affiliated with LTT.