This is a sim racing steering wheel that can handle 16 buttons, and you can choose to mount two encoders.
This is the second iteration I've made for this project, and it has been working very well for a year on a direct drive (DD) hoverboard base that can deliver about 10 Nm of torque.
The steering wheel weighs about 750 grams, which is lightweight compared to commercial ones.
With the exception of the handles and paddle-related parts, print everything with 100% infill.
The project can be printed in a 250x250mm printer.
There is a small gap between the front plate towers and the box towers (0.5 mm). This may or may not work for you, depending on your printer. It worked well for me, but I had to add a washer to the top middle tower; the others accommodated the gap well.
The Arduino code is attached as well. The encoders are set to deliver both button presses and an analog value; you can choose what best fits your needs.
The author remixed this model.
The original model is based in a metal plate, mine is completly printable with a bipartite front plate that can be printed in a 250x250 mm printer. I made a lot of other changes, like double paddles, changes in the handles, reinforcements in general, holes to fit hex nuts and etc