In Jon Favreau's version of John Carter of Mars, John would have woken up in the middle of Barsoom, next to a Thark Incubator, where the eggs of baby Tharks are kept until they hatch. The challenge was to come up with a design that used neither wood nor metal. I devised a crater-like space covered by tanned Thoat hides stretched over a bundled reed structure, itself held in tension by stone weights.