I went about modifying Zack's original model since I don't need 6 spots for nippers. Honestly, not super happy with what I came up with, and as I was working on it I realized why the original was the way it is. However, I'm releasing it anyway since it's what I'm using for now, and maybe it's just what someone else needs.
Zack's original design is a pretty good balance since it fits 6 slots in a 4x2 grid. This is possible because of the way he spread them out, but making one that's 2x1, 2x2 etc would mean changing spacing between racks, which is already pretty ideal. One thing to note about this 2x1 design is that you absolutely need magnets/screws or it falls over with a tool in it. It also hangs over into adjacent grid items like the original, which isn't bad if it's at the end of your grid but it doesn't fit well in smaller grids.
I should have centered the piece that the nippers rest on more, but rather than improving this design I'm brainstorming other ideas that might be a better use of space and still sticks with the Gridfinity principals of displaying the tool and making it easy to find within a cluttered grid.
f3d and STEP files included for anyone that would like to modify this further.