Need help with diy mintypi

[Reaper]

I'm trying to make a mintypi as cheap as possible and I am don't know what gpio pins to solder my homemade gamepad into as this is the first thing I have tried to make with a raspberry pi. Also is there anyway to make my own powerboost or something similar to it.

Pics of homemade gamepad.

1559177571001982683036414030216.jpg (2.64 MiB) Viewed 1608 times

15591776207555176325340405699384.jpg (2.4 MiB) Viewed 1608 times

[LilTrublMakr]

https://pinout.xyz/

You can use pretty much any of the pins circled with green and then set the GPIO (BCM on that site) number (NOT THE PIN NUMBER) in your config file.