This Japanese site has several paper models of aircraft and motorcycles. None have been added since about 2016. There are also some computer-generated graphics of the aircraft, and photographs of some plastic models.
The owner is Kouzou Murakami, going under the name "Kozin", which is what I shall use here.
Designs are first done as a CGI model, and adjusted to look "right", with apparently not very much hard measurement. They are then automatically unfolded. For the earliest models gluing tabs were added by hand, but now all this is done using Pepakura. This leads to some rather odd part shapes and awkward construction of the more complex components, but good fit once the problems are overcome.
Updated February 2022