I used the base gridfinity shapes available in the Sketchup 3D warehouse to build these on. These holders might not work for your sockets, check the spacings between the posts. The spacings for the smallest sockets have 10mm between posts, the middle set starts with a 9mm gap, then 11mm, the last 3 are all 12mm. The large set will hold 4 sockets with 23mm diameters as well as a couple of adapters.

I used 8x3mm magnets as those are what I have handy at the moment, If I did these again I would use smaller magnets and put them in the sides of the posts.