I am concerned about the post-build finish of the balsa prior to covering
Once smooth to your satisfaction, it is important to get all the sanding dust off. Wiping it off only serves to grind small dust particals into the wood grain...the best dust removing method prior to covering is the good old vaccume cleaner!
As for a field box...here is one of MANY threads on the subject!
http://www.rcuniverse.com/showthread...331&forumid=22]