These free plans are to build a hovercraft. Yes. Hovercraft plans.
From the plans:
You're almost ready to believe in flying carpets when you open the throttle and see a 200-lb. load float eerily off the ground. Tip the handles slightly and you have to brace yourself to keep this wheel-less Flying Cart from skittering down the drive faster than you want to follow.
More—you can easily trundle a 100-lb. load across a soft, soggy lawn with this machine and never leave a mark.
The Flying Cart is a true ground-effect machine (GEM). It has no wheels. It glides on a cushion of compressed air supplied by a modified chainsaw engine and a four-bladed wooden prop. I built the "airframe" of ordinary lumberyard materials.
How it got that way. The cart didn't start out as a search for an improved wheelbarrow—it happened the other way around. The building itch came with the first story I read about air sleds, and intensified with each story thereafter. It was a challenge to build a totally new kind of vehicle before all the development problems were trampled to death—and all the unanswered questions were answered—by multimillion-dollar research programs.