I am so thankful for what you're doing and for sharing your knowledge so openly. I feel that I have to construct the speaker now (I've already started ordering parts).
Constructing the crossover is the least of my worries. I come from a synth diy background so I am very familiar with designing and constructing pcbs. Cabinet making and wookwork is on the top of my worries, I will probably have to find someone knowledgeable here to construct it. I have a lot of questions about the cabinet making procedures but I won't ask anything now because I am currently going through the forums.
Concerning the horns I had the idea to order a horn locally and then tweaking the crossover according to your crossover technical documents (I've even downloaded AIM spice). It would be great if I could manage that, this way you learn something. However it can be very challenging for the first build. I will get the horns from you. It's not shipping costs that worry me (they are substantial though), what I am worried are the ridiculous customs charges when importing.
I am very excited about the project. Thanks again.