Want some inspiration for building lightweight yet rugged units? Look to the R-C Airplane modelers. They have been researching and developing methods for lightweight units for years. To say that they need to also be rugged is obvious. When is the last time you crash-landed your module from 100 feet?
The aircraft industry, mainly the Experimental Aircraft crowd is also a good resource. Not only can you gather ideas and construction techniques but their suppliers also carry many, if not most, of the more esoteric supplies you could need.