Curtain track connectors
After owning a 3d printer no more than a year I am still blown away from time to time by being able to make plastic replacement parts at home.
This weekend I was putting up some curtains at home and realized I needed to extend the tracks more. The IKEA Vidga track only ship with two connectors and if you want to cut the rail in two and use both parts, your short of connectors. (Not even sure these connectors are sold separately.)
The ones I made are simpler than the original part. which has a lever to hold it in position. Mine relies only on friction to stay in place.
If you need some of these too, they are here on Thingiverse. And should you need to do any customizations and rather not start from scratch the Fusion 360 file is available there too.