I'm in the process of redrawing the plans now. It's going to take some time, but I'm hoping to have them all ready by the end of the month. In the meantime, there's enough information to build them and I can help you with it if need be. I've sent plans that you can use for the base, and you can build the midhorn as shown here. Cut sheet drawings are shown on the "Horn Basics" page.

The base π cornerhorn is the same as shown in existing plans, just like shown in the PiAlign document. Just put the midrange horn on top of that. The tweeter horn can be mounted flush in the base cabinet or on top of the midhorn, just as long as the mouth edge of the tweeter and midhorn is flush and they are physically close vertically, within a nine inches.