The author remixed this model.
These fits 3/8" drive hex bit sets I have and I have created versions for other common variations based on available dimensions. These will hopefully work for you if you have a set that matches one of the combinations below.
These should work for impact or standard bits, thought the standard ones might be a tiny bit looser.
Check the hole sizes by either by measuring hole sizes or move the blocks partway through the build plate (so the first layer has the holes in it) and print just a couple layers.
If these don't work for you you can make something similarly sized for your specific sets with the parametric files here
The bottom is 21mm gridfinty squares which are compatible with the standard 42mm grid.