Here is the Sky Pup ultralight aircraft. There is much polystyrene foam in its construction as well as a light wood – I think some balsa wood. it is a gentle conditions flyer, and it has a classic aviation look. One thing though, is it has no ailerons.
The Pup’s design has some good aspects, such as streamlined airframe, well layed-out weight distribution and simple sturdy construction.
But if I were to customise it for me, id make the cockpit headroom taller, and add ailerons. Id also probably enlarge the tail plane and fin. its an older design so probably has a 20hp half vw type motor, id strengthen the firewall area and add a 65hp rotax 582, or a 65hp Hirth.