I replaced the crank on my tandem bike with one that has a 50t and an 34t chainring I fond online: https://de.aliexpress.com/item/1005002006418047.html

Unfortunately this model was provided without a chainguard so I 3d printed my own chainguard. It is mounted using m4 sinkhead screws. The screws were cut to their desired length using a dremel after they were screwed in place and secured with a drop of locktight. After cutting the screws they were deburred using a circular grinder.

This 3d model only fits on the printbed of the Prusa i3 when disabeling the skirt!