Partially 3D-Printed DIY Footwear

This Sole product, by Etsy seller Roussin, is a novel take on DIY footwear.

The idea is that you 3D print the sole, which "has integrated holes around the edge for attaching elastic cord, textile cord, or other materials."

You then knit your own upper, and attach it through the holes:

Roussin sells the .stl files for $10. They're for foot size 25-25.5cm (US men's 7-7.5, US women's size 8.5-9) so you may have to scale up or down.