Sokol1_br

So the more easy way to make this a "joystick controller" is flash - using the USB cable; with MMjoy2 firmware, after make the configuration (number of axes, buttons, encoders) is done though MMJoySetup GUI. Well explained there: https://www.sas1946.com/main/index.php?topic=58176.24 Other option is RealRobot configurator. https://gitlab.com/realrobots/rr_configurator

What Arduino? Some models don't have USB, need to be used as "joystick controller".

The +5v x Gnd swap means that axes will work work inverted. For rudder axis is not issue, just use the invert axis function in games for correct, but for brakes pedals maybe result always pressed for Windows/Games. Since for solve the issue is need make solders, the easy practical way is swap this wires in the pot pins, if don't carry about "keep original".

An example of motorcycle damper installation in T-Rudder (original in Russian, use Google Translator), seems without need of extra parts, modifications - the front bar was replaced, but for fit the pedal in a tubular "cockpit". Damper used: https://www.aliexpress.com/item/3256801750892991.html?sku_id=12000018160196309&spm=a2g0s.9042311.0.0.125433edNtmRU8&gatewayAdapt=4itemAdapt

Any idea where this topic is? I found nothing so far. Just in case, fixed on top of Input Devices (this forum section)

What is "JF-Flyers joystick"? Anyway, I suggest you ask in Reddit/r/HOTASdiy, there people use write code for non conventional joysticks. BTW ATMEGA328 don't seems a good option for joystick controller, since need include USB support via software.

For replace OMRON B3F-100 micro-switches is more "bullet proof".

See if this tutorial help:

In the software - that configure the firmware; disable the logical button, so the press is no more registered as DX button.

Depends on where (corner of the world) you live can order PCB from OSPark, Debelestis upload there layout for 8, 16, 24, 32* button CD4021 Shift Register boards. *Can chain boards for more buttons, e.g. four for 128. https://oshpark.com/profiles/Debolestis Or download the file for DIY, order the PCB from another PCB service. An detail to observe, you need a USB controller with support for CD4021 Shift Register, e.g. Freejoy and MMjoy2 firmwares for STM32f103 and Arduino PRO Micro, Micro Teensy 2.0, ++2.0 cards.

An more simple way for have this "twist brake lever", without having to create a new virtual axis. Just need change one parameter of the original configuration for twist axis (#3 Rot X) for the axis became a full axis (0 - 100%) with just twist for left. Change the tick from 1 to 2. 1 un-ticked remove the center position of the axes. 2 ticked invert the physical data. If not ticked the axis varies 0 - 100% with twist for right movement of the grip, what is less ergonomic, comfortable.

PCB layout for these Shift Register (CD4021B) boards for 8, 16, 24, 32 buttons are in OSPark/Debolestis. You can ordem from there, or download de the file and send for your preferred service. https://oshpark.com/profiles/Debolestis/page/2

Metric dimensions: https://arstechnica.com/gaming/2018/09/thrustmaster-tpr-is-the-king-of-mass-market-flight-sim-pedals/

This guy create a 3D Printed "clutch" system for T-Rudder. https://youtu.be/IGou-WhwEHI