That's really cool. Are you going to use reflective material or insulation, or will it be purely for warm weather use? I've played around with welding plastic, and I can hardly wait to make one, but I've got CCF pads, and I'll probably use a frameless pack, which I need the foam pads for. So, it's really not necessary for me to build one, just a cool fun side project. Post lot's of pictures for us.
I plan to put down in it. But I am still kicking around putting some reflective material in it.