CheckOut mutantC_V4 as it is successor of this from here.
Take a look at this in 3D using AutoDesk Fusion 360 Online.
A Raspberry-pi handheld platform with a physical keyboard, Display and Expansion header for add-on boards (Like Arduino Shield).
Here we will discuss what you need to build one. This device is very easy to make, you don't need lots of tools and parts.
No codding skill is needed. just basic stuff like upload a code to Arduino, little skill in Linux CMD line to install the driver. Little soldering skill that's all.
You need this parts to make one for your self (this are not affiliate links):
All the 3d parts, PCB and Gerber files, keyboard firmware are in Gitlab and free to download and use:
I added the build guide in Instructables as it is perfect place for it: