This homemade device can be used for doing thread milling on a manual milling machine.
The device uses a "nut and bolt" set for creating the thread cutting motion. Each "bolt and nut" set can be used for milling one pitch value when doing thread milling, and the diameter of the thread can be variable, as long as they have the same pitch. Also, it can be used to cut external and internal thread.
You can change the "bolt and nut" set to change the pitch.
The prototype version I made on this video is for demonstration and education purpose only.
It can only work on soft materials, because of the low rigid, low precision of the components and hand operation.