I kept worrying about loosing these clamps. I found a chinese supplier for the whole thing, but it was kindof expensive and I'd have to wait a month.

I took the STEP file from the ultimaker github, opened it in Freecad, exported it as an OpenSCAD and then rendered it there as STL.  (EDIT: I missed the fact that you can directly export STL from freecad)

I printed a bunch because I find that small things like this benefit from time to cool before the next layer is applied, The printed locks aren't identical to the original, but they work fine. PLA is a little stiff, so another material would probably be better.

The polygon count is kindof low. I barely know how to open freecad, so maybe someone else can do better. The STEP file says it was created in solidworks, but I'm not rich!

Note, the Ultimaker files are licensed non-commercial, so I transferred that aspect to this as well