At the heart of this thoroughly trippy house near Woodstock, N.Y. are tales of the Muppets and Jim Henson, The Grateful Dead, and their biggest LSD supplier, and that’s not even the half of it. The real visionary here was the home’s first owner, artist, engineer and master set designer John Kahn, who built the one-of-a-kind house over 15 years. Kahn was a friend and collaborator of the late Muppet creator, and he designed sets for the “Fraggle Rock” touring company and more. Kahn used re-purposed materials including slate, copper, aircraft-grade aluminum and redwood as well as local wood and bluestone to craft this cylindrical work of art that never seems to look the same way twice. The three-bedroom home spans 3,518 square feet and is asking $1.2 million.