Wood router circle making/cutting jig buying guide. router jig is an integral part of woodworking. whether you are an avid carpenter or like making diy stuff with wood panels, it’s hard to overlook the need for a perfect circle jig for router. after all, the jig quality will decide how accurate your cutting is.. The jig’s working area allows wood as thick as two inches and works well with all kinds of shapes up to 3/8” inch in size. all available five guide holes come with varying hole sizes that can be used in different woodworking applications..