Simple button box for simracing and other activities. This works but its still an early phase and I hope to subject it to a great list of improvements from polishing the 3D models to making the whole thing more compact.

Components

Electronics

Part	Quantity
Arduino Pro Micro (ATmega32u4)	1
Female Headers for pro micro	24
JST-PH Connectors (6 pin) male and female	1
JST-PH Connectors (5 pin) male and female	1
JST-PH Connectors (3 pin) male and female	1
JST-PH Connectors (2 pin) male and female	3
Perf boards 70mm x 500mm	2
100nF Capacitors	10
74HC595N Shift Register	1
74HC165N Shift Register	1
10k Ohm Resistors	20
1N4148 diodes	26
Toggle Switches	6
Rotary Encoders	4
2P LW26-25 series changeover switch	1
MX switches (and keycaps I recon)	12
Wiring and consumables	Lots

Hardware

Part	Quantity
M3 nuts	20
M5 nuts	2
M3x40mm	4
M3x12mm	2
M3x50mm	4
M5x20mm	2
M3 t-nut	2
M2 Heat Inserts	7
M2x6mm	7

3D printed parts

Clamp: composed by the files ./3DModel/seatAttachement_screwSide.FCStd and ./3DModel/seatAttachement.FCStd, the latter is the the one facing the seating user and the first the one facing outwards
Arm which is the file ./3DModel/arm.FCStd
T-slot which bolts to the front plate: ./3DModel/tSlot.FCStd
T-slot bracket which bolts to the t-slot and the arm: ./3DModel/tSlotAttachement.FCStd
Front plate where all the buttons are mounted to: ./3DModel/frontPlate.FCStd
Cover plate which where the "pcb" mounts and connects to the front plate: ./3DModel/pcbHolder.FCStd
Very simple knob for the rotary encoders: ./3DModel/knob.FCStd

Assembly

The assembly is straightforward, specially if you are the one that imagined it:

put the toggle switches into their through holes and bolt them
put the rotary encoders into their through holes and bolt them
insert the MX switches into their holes
bolt the changeover switch into its slot
wire the things according to the schematic. I started by doing the columns and then the rows and left the rotary part of the encoders for the end. Crimp the JSH-PH connectors on the rows, columns and rotary encoders
solder the components to the perf boards. I joined the 2 perf boards like the images show
mount the back cover
1. put the heat inserts into the back cover
2. bolt the perf boards to the back cover
3. drill holes on the front plate for the back cover holes. They go 7.5mm in from the front plate edges, 1.5mm below the toggle switches and are spaced apart by 45mm
4. pass the M3x50mm bolts trough the front plate and put nuts holding them
5. place nuts 8mm down from the tip on them
6. connect the front plate electronics to the pcb
7. place the back cover on the M3x50mm bolts and put nuts on it
bolt the t-slot 3D printed part tot he front plate and pass the t-nuts into it
place the t-slot attachement on the t-nuts. Leave them loose for later adjustments
heat insert the M5 nuts into the arm and the M3 nuts on inside part of the clamp
loosely assemble the arm
place the assembly on the playseat and clamp it down with the M3x40mm bolts
do the final adjustments and tighten everything down

Schematics

Well, I'm not very well versed on KiCAD or eletronics design in general, so all I have is the following hand drawings and pinouts. I will make something better at some point.

Shift registers:

Pro Micro Pin	74HC595N Pin
4	14
5	12
6	11
GND	8
GND	13
5V	16
5V	10
Put a capacitor on the 5V and common Ground

Pro Micro Pin	74HC165N Pin
7	15
8	7
9	2
10	1
GND	8
GND	13
5V	16
Put a capacitor on the 5V and common Ground

Shift registers to kbd matrix

Rows on the 595N:

74HC595N Pin	Matrix Row
1	5
2	4
3	3
4	2
5	1
6	0

Columns on the 165N:

74HC165N Pin	Matrix Col
14	4
3	3
4	2
5	1
6	0

Rotary Encoders

Referring to the rotary encoders from the front view. Only the first one will have the common ground specified because thats the one that runs the ground for all the others.

1st: