I have a plunge router but have never tried insoles . It became necessary to create a bow tie/bow tie to further strengthen the cracked joint that would be stressed. This kit makes it possible. did a test run. found it works as advertised. moved on to the actual project. worked well there too. Inlays and patches somewhat limited in depth by the length of the 1/8 cutting tool. it's probably for the best. too long and the tool may bend under stress, resulting in inaccurate cuts on the male or male part.