This model will enable the creation of a holder for Jorgenson style F-clamps. (Harbor Freight clamps will also fit. By combining a left end section, a right end section and an appropriate number of center sections, holders with variable number of slots can be created. I used the STL files within Onshape, but presumably other CAD tools could also be used.
Edit: Added 6 slot holder, as it was the only one missing.
The author remixed this model.
Starting with the 4 slot clamp holder from Pending Progress, I created a left, center and right section. By combining the end pieces with several of the center pieces, a longer unit can be created. The 8 slot example is one such case. 3 center sections along with a left and right end piece were used.