Go to Sig's website and take a look at the Kougar and King Kobra. Both where designed as a 3rd plane in Sig's training line. They are not difficult to build and will expand your building knowledge by teaching you how to work with a foam wing.

BlueJay models is producing the old Bridi line of planes. The Kaos and Super Kaos will also make a great 3rd plane. Besides being classic pattern planes, they also make great sport planes.

Hogflyer