For the .40 size trainer... look at ww.spadtothebone.com the trainer is the "Debonair". However, with some flying skill already... there's an "Ugly Stick" sort-of-clone and a few others which may be more suitable. The Debonair can get a bit boring to fly for some people...

I'm working on a .15 to .25 power SPAD trainer design... can scale it down for the .074. (its mainly how to keep weight down that would cause problems with coro construction and the .074.)