Bow string jigs are tools that assist in the preparation of bow strings. Basically the jig is a pattern from which you can build the bow string itself. They also help you by having a set work area for your bow strings, which helps make the process more uniform and safe. Commercially built bow string jigs are available, however it is relatively easy to build your own with just a few household items.
Cut the 2-by-4 to 7 feet long and then use the measuring tape to measure and mark the centre (lengthwise) of the board. Measure out from either side of the centre line and mark the board in 1-inch intervals.
Screw one screw in one side of the 2-by-4 on the mark for half the length that you want your finished string to be. Then repeat the process on the opposite side.
Use the string jig by wrapping the bowstring around the two screws until the desired thickness of string is achieved. Unscrew one of the screws to remove the string and adjust the length of the string by moving the screws further or closer from the centre line.
If you make alot of strings that are the same size, you can make marks on the 2-by-4 for where to start and stop the wrapping for the nocking area on the string.