I’ve designed the PCB! Here’s a picture: 

I’ve had some confusion about the buttons, due to how easy easy designed it. However, I’ve made a simple be version of it on a breadboard, and it works fine.

I’ll probably order the PCB from JLC pcb, and It’ll probably take 2 weeks. I have a Raspberry Pi and buttons, so all I need to get is a 30 pin header and a 128x64 OLED screen, I’ll order that from eBay.

In terms of size, I don’t completely know, but judging from the picture above, I’ll bet it’s 4.5cm by 8cm, just because I know that the raspberry pi zero is 3cm by 7cm.

Regardless, it’ll be small enough!

I don’t know what I will do for the battery, but for now I’ll use a power bank. Maybe I’ll take it apart and hack it.