When I was developing these horns, I made several versions with different throats and different mouth sizes. The last few models were only slightly different, and we really only different because we were deciding how to manufacture them and what cut angles to make. The biggest issue we had is with wood thickness. You need different cuts and jigs for each wood thickness.The basic dimensions shown in the plans are simplified, and you'll need to setup cut dimensions and angles for your wood. We have three different jigs for different various wood sizes. The first horn is the hardest, and after that, they go pretty easy. That's why we make flat pack kits available, because we have the production issues nailed down. This makes it easier for DIY builders that aren't setup to do precise angles and what not.