Wanted a reduced angle grip for an HPA drop-ins and could not find anything, so I butchered a file from Igniz on Cults3d(https://cults3d.com/en/3d-model/various/aeg-ar15-pistol-motor-grip-1).
The remixed model doesn't look all that great, but it feels solid and did not seem to have any issues with installation other than needing a little sanding. You can get away with using the original philips screws that attach most grips, but it is pretty finicky and you will probably strip them eventually. Hex screws and a ball end hex key are probably the way to go. The 15° is significantly easier to install than the 5°.
Added a "for grugs" 5° with holes for an allen or philips to go through on the back of the grip.
The author marked this model as their own original creation. Imported from Thingiverse.