The drawings show panel cuts, so since they are at an angle, they are the hypotenuse and longer than the axial length of the horn. What might be helpful is to cut out a cardboard horn using the drawings and you'll see what I mean. That's actually how I did the prototypes - I did the drawings, then cut out cardboard pieces and made mockups, and then I took those to the cabinetmaker to build.We also have midhorn kits that are cut perfectly, and the fit is excellent. That makes assembly a lot easier.