This model is being offered for free because it is a work in progress!  I have yet to test fly this model.
 
this is a seriously advanced model designed to maximize the strengths of 3D printing processes.  This model has CnC milled reinforcing parts in key structural areas as well as a vacuum molded canopy, fiberglass cowling, and wheelpants.  
This is a traditionally built up and covered model desgned for printing in PETG filament.  All parts interlock in a jig type assembly for accuracy and ease of construction.  Think of your printer as more of a 2.5D CNC sort of solution but instead of cutting you are printing highly intricate parts impossible by traditional CNC methods.  The parts are oriented to print quickly with the most strength and the lightest weight possible.  Once assembled you have a model that far exceeds the strength of a traditional 3D printed plane at the weight similar to traditional stick built style models.