I'm in the process of building aluminum cases for two Zizzo folders my gf and I just bought. I'm keeping them under the size limit to be safe, but because they also convert into trailers (to haul carry-on) and are relatively beefy, I'm bumping up against the 50 lb weight limit for economy seats. Right now I'm scratching my head as to how to incorporate casters and center stands with only 1 lb left to play with. :|