When we moved from an apartment with a roof hight of more then 4 meters to one with about three meters, the cabel of our lamp was way to long. I didn't want to shorten is by cutting the cable. The solution was to design and print this tool.

Just hang it to the cabel, then twist the cabel around ist and pull it through the second hook. You can easily see it in the pictures.

Let it hang loose and tadaa.. works perfectly as a nondestructive way to shorten a cable.