OttoDIY for M5Stack
Print each STL file on the required number of 3D printers.
I currently use a bulk battery that no one can buy.
Battery holder (M5Stack-OttoDIY_batteryHolder_v1.stl) needs to be changed according to your mobile battery.
Create a circuit on the M5Stack Proto module so that an 8p pin header emerges from M5Stack-OttoDIY_base_v1.stl.
M5Stack-OttoDIY by Takao Akaki is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
Based on a work at https://www.thingiverse.com/thing:1568652/ and https://www.thingiverse.com/thing:2892903.