When my string serving started to unravel, i decided that i want to try out 3d printed serving tool. I found one on thingiverse, even though i don't like these type of serving tool i printed and used it to make serving on string, it worked, but i was used to Beiter style tool.
This was a cause to designing this one. It is still a prototype, i used it to create quite good serving imo.
If you don't know how to use it, i recommend looking at Beiter website.