I created this grip for my mom who is getting older and she found that holding the GBC for extended periods of time wasn't comfortable for her. It snaps into place using the screw holes in the middle of the device.
It will need supports to print, I recommend supporting from the bottom of the two handles and angling so the rest of can be printed without supports.
UPDATE April 13, 2025: I've added a step file for the model so it can be easily remixed for anyone that wants to.
The author marked this model as their own original creation.