I designed this GoPro handle for filming at the Maker Faire. This is the "basic" version of the handle but works quite nicely! The handles are held to the body with 1" long 1/4-20 screws and 1/4-20 nuts epoxied into the handles. Image shown has first gen base FYI.

You will need to print 1 top handle, one handle basic 1 and one handle basic 2. Also you will need 2 handles no o rings. These have the hex molded in for the 1/4-20 nuts that get epoxied in place. I tried to design enough tolerance gap but you may need to re-enlarge the holes with sandpaper or a 1/4" drill bit.