This is a 3-button joystick I designed specifically for my Amiga, it seems only few games support the third button, but handy for the ones that do, like ADOOM and such. This remix I kept the basic shape, but shrunk down for the smaller amount of buttons and to fit on my 150mm x 150mm print bed. I have entirely redesign the bottom portion to fit the top.

I'm using the small Joystick and Arcade buttons from Adafruit, but you can likely source these from elsewhere.

https://www.adafruit.com/product/480
https://www.adafruit.com/product/473

The top lid in the original design is held by M4 x 10 bolts and hex nuts and I kept that in my this design. but for my build, I found some self taping screws that work just as well. The cable I used is fairly thick, if you use a thinner cable, you may need to change the hole the cable passed through or use some other method to ensure that the cable won't move if tugged on. It's possible you can find a plastic cable strain relief grommet that will work well.

For wiring details I got my information from here: http://wiki.icomp.de/wiki/DB9-Joystick
Some may want to wire the third button to imitate Joystick UP for some games if they prefer to jump with a button. I ended up adding a toggle switch so I can switch between using the third button and having it act as an UP button. It's also likely you can adapt this joystick to other systems without too much issues. The link above shows the wiring of several different computer/game systems.