Last night I was out on an adventure. In the morning, the shower curtain fell down because the pole was a bit too short. After I pulled the paper towel tube shim out, I tried to twist the rod to lengthen it. Since it was maxed out, it needed a little something special to help make ends meet.
When I went downstairs, I took a few extra steps out to the car, got the Makerbot and returned to fire up the computer with Sketchup. It took two iterations to get the dimensions right. The new part came out sized to fit over the end of the curtain rod and take up a bit of the gap.