Do you know of any communities with self-built airplanes? (especially novel-esque designs for propulsion or wings?) I realise these have far more regulations, but experimental GA is something that really excites me.
They have had a handful of articles of people working on electric propulsion in their magazine. I would imagine you could reach out to some of those featured. I once contacted a person who was building a DIY HUD and he was very friendly and eager to talk about the project. Overall a very good community!
He's actually building out an aviation park to promote the community: https://www.youtube.com/watch?v=IenxeMl2nkw
Just yesterday I stumbled upon https://vesc-project.com/forum where they are doing something similar with a focus on ebikes and drones.
You are talking full-sized aeroplanes right? I think some of the sail-gliders can be homebuilt, there must be communities for those guys.