Ergonomic grip for Canon F1 (not F1n).
Print this with thick walls, thick upper and lower shells, and out of something strong like PETG or PC.
attach to camera with tripod screw like this one: https://www.amazon.nl/statiefschroef-snelsluitschroef-camera-bevestigingsschroef-camera-statief-snelwisselplaat/dp/B09CYNFNXG/