Woe unto the pilot who carries his planes about in an unboxed manner! Needing a box to carry my DLGs in to an out-of-state contest in the back of a pickup truck, I quickly hashed out the plans to make one out of a single sheet of coroplast. This design allows for a 60" wing (or a 60" wing segment) and comfortably and safely holds 3 fuselages, 3 wings and I even managed to get the wing for my 2-meter Allegro-Lite in there as well!
I procured the sheet of corogated plastic (coroplast) from my local Fast Signs shop for $40. Using a yard stick, a utility knife and some gaffers tape, I whipped out a box in under an hour. Wal-Mart sells (on occassion) a 1' cube of dense foam for about $11, and using a long knife I cut it into four (4) 2" slices and one (1) 4" slice. Clasps were made using some utility/backpacker rope and two large buttons. A handle was fashioned out of some of the scrap coroplast and taped to the lid. However, I found that the adhesive in gaffers tape, while marvelous, does not stand up to midday sun very well. Instead, I used some nylon bolts and nuts (handy for when I forget my wingbolts).
The plans (just a JPG) are located in the Travel Boxen gallery, linked below.