I described this as"scalable" rather than “parametric” - the clear opening dimension of the model is 25.5mm x 4.4mm and it's a very easy calculation to measure the size of your chisel and scale the relevant dimension in PrusaSlicer.

Link to my PARAMETRIC Onshape File can be found at the bottom of the “Download Options” (in fine print!)

Alternatively I'm happy to add additional sizes on request.

Because the tip angle of the cover is deliberately much steeper than any chisel sharpening angle, there is no need to be absolutely precise in your calculation, the chisel will jam in when the tip is pushed firmly to the end.

I have used PLA as an experiment, and it's fine.  PETG might be a little more forgiving perhaps, and a flexi filament would be the cat's whiskers!

This one was printed as per the attached file - 0.4mm nozzle, PrusaSlicer PLA 0.2mm QUALITY setting with no support necessary.