What I would love to build had I actually a proper garage, would be a Floyd Fronius GOAT or BUG. Both ultralight, stick and rudder gliders. Quite a few GOATS have been built around the world now. Also, unfortunately, the UK aviation regulations are particularly unfriendly to such gliders, classing then not with hang gliders and paragliders but with full size sailplanes. The late Fred Hoinville had a almost messianic fervour for getting people in the air cheaply in Australia, and had a 30ft max wingspan fixed in his mind. He died in the 60s, but the dream has been realised now.