Born out of need, this reel has a simple story: Minox group – Flickr thread
DIY job as appears to be done by Jimmy Li
When a Minox tank or similar device is not available, you may want to modify a regular 35mm developing reel. Especially suitable for developing color film, since keeping a constant temperature with Minox tank is often a game where you loose. Obviously, you can modify the 35mm reel to accommodate any film format in between: 16mm / 110, Hit 17.5, 127. I am not sure if you can modify the reel to accept 8mm, the tiniest format I know. The 2 parts of the reel are very close to each other in 9.2mm format; I am not sure you can cut down the reel to take 8mm size.
Courtesy to Jimmy Li (and copyrighted to him too).