Simplest print 2minute design on Tinkercad this and another quick design available on Tinkercad as BowStringServer

Simple bow string server for making repairing bowstrings for compound, recurve, crossbows.

Simple design to print add 85mm M6 Bolt Machine screw, 2 x M6 washers, M6 Wing Nut and its ready to use, depending on your printer quality you may need to drill of fille the 6 holes as you do not want to fray serving thread.

Enjoy