The original grip design is by Scott Garriott, you can find his model at https://grabcad.com/library/e-m5-mkii-diy-camera-grip-1
I know EM5mk2 is a 2015 camera, I use my design for a long time until my friend ask me to share it.

I tweak some detail:

1. The Garriott design bottom is 6 mm, so many tripod plate can't reach. My design reduce to 2 mm. Of course it will become more fragile. So it is suggest to print with high strength material.
2. So I increase the "front bumper" thickness
3. Add groove for thumb
4. Add slot for micro SD and micro sim. (I've tried large SD, it has solution, but ugly :P )

Please notice:

1. The grip fit to camera tightly.
2. Due to PLA is harder than EM5ii coating. And I doesn't have suede as buffer. So my camera's body coating has some flake-off.

After all the most important thing is it is a grip which suit my hand.

Creality

Ender 3

No

Yes

15%+

1. The most important is to use high strength material, like CPLA, HCPLA, Carbon Fiber PLA, Nylon. The transparent PLA is hard but crunchy.

2. The best setting is
   0~5mm: 1~1.2 mm layer height
   5~50mm: 0.3 mm height
   50~: 0.2 mm layer height
   Why? Because 0.3 mm can give better friction

3. Also you can choce frosted PLA for friction