RE: electric PBF
Have built many out of blue fanfold, depron, pealed foam board, etc. A GWS IPS motor and two or three lipoly's along with a piece of foam about 16" or 18" seems to be a good size. Building them with a airplane profile body works well as well. Add a rudder if you want to do any hovering.
KsFlyer
Av8 Hobbies.com