Filling, sanding and finishing the wings is a lot of work. I enjoy the scrounging and improvization aspects of plans built, but it takes a lot of time that I could have spent completing the project ahead of life's unexpected events. _Don't_ take my route of slow & cheap - buy the Durabond boards and/or 3M Cubitron paper.
This is also a spot to store the instructions on attaching the wings - plan on buying the bolts in several sizes so that you don;t have to measure, then wait for delivery of the correct ones.