Stream Cheap with PCB design to allow for easier install so you only have to solder 9 wires. Can be used to create a hotswapable version via millmax sockets. Can also be used with a Nice!Nano V2 so you can include a battery and make it wireless. Here is my ZMK config for it that includes zmk studio support https://github.com/luigi311/zmk-config/tree/stream_cheap_2x4. Washers are included to cover the pcb from the side so it is not visible. Faceplate isn't the best due to how flexible it is so getting something stiffer is recommended but needs to be designed.

PCB
https://upverter.com/eda/#designId=98f9dd31c60d034f,tool=pcb
Export as Gerber Format (RS-274X extended) to be used with JLCPCB or other sites

Micro controller
https://nicekeyboards.com/nice-nano/

Batteries used should last about 8 months +- 2 months according to the ZMK profiler
https://www.amazon.com/gp/product/B08TBWKBD5/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

JLCPCB print settings used.

Build Time: 3 days

Base Material: FR-4

Layers: 2

Dimension: 85 mm* 42 mm

PCB Qty: 10

Different Design: 1

Delivery Fomat: Single PCB

PCB Thickness: 1.6

Impedance: no

PCB Color: Black

Silkscreen: White

Surface Finish: HASL(with lead)

Deburring/Edge rounding: No

Outer Copper Weight: 1

Gold Fingers: No

Flying Probe Test: Fully Test

Castellated Holes: no

Remove Order Number: No

4-Wire Kelvin Test:No

Material Type:FR4-Standard Tg 130-140C

Paper between PCBs:No

Appearance Quality:IPC Class 2 Standard

Confirm Production file:No