I took this photo while testing my solar hot air balloon. It's much bigger than it looks from this angle. It's filled with air by hand then the sun heats it up and it rises. It's made by cutting off a 30ft * 15ft piece of 0.3 mil painter's plastic drop cloth, folding it in half and sealing the remaining edges with clear packaging tape. The pillow shaped balloon then has one corner cut off and a cardboard mouth/ring put in for filling and the tether. The dark coloration is from air-float charcoal put inside and shook around till it coated the surfaces. These types of balloons can lift about a pound to over 60,000ft. But until I can fulfill the regulatory requirements of positional reporting these are just tethered tests.

Now that I've figured out construction and everything works I'll move on to making a proper large envelope with normal diamond-like gores joined with strapping tape to distribute the load.