1/4x20 to 3/8x16 tripod screw adapter

thingiverse

I purchased a tripod head, but it took 3/8x16 threads. I wanted to be able to mount this one on top of a tripod shoe, so designed an adapter with 1/4x20 threads on the inside. This took a few iterations. Settled on a large handle for screwing it in. While the outside threads printed and worked easily, the inside threads were tight. After a few attempts at making the hole larger and threads smaller, I was finally able to get it to accept the 1/4x20 screw smoothly. Your mileage may vary.