According to Wiki, a few AC-4s were built in Britain; I recall one of them experiencing flutter during a test flight & the pilot bailing out. Apparently kits are
available again. Handicap of 85, the same as a Grob 102, so you can almost certainly buy better performance second hand for less than the cost of the kit.
The first
HP-24 has just flown. He's pricing kits at US$30,000 (no trailer) & claiming an L/D of 42.
There's plenty of 'homebuilding' in the vintage scene.
I always fancied one of
these.