After a random chat with radiantbaby, vatavian, and rslatkin, I've become obsessed with the idea of an adult-sized ball pit, particularly with potential application as a bed. The big question in my mind, though, is one of volume. How much floor space would it need to take up to comfortably sleep -- or play -- two adults? Four? Six? And how deep would it need to be to support them? How does intended activity (sleep, ball-war, sex) affect the depth? And can a deep pool be used for shallow-pool activities like sleeping? Or would people just sink in uncomfortably?
"How much floor space would it need to take up to comfortably sleep -- or play -- two adults? Four? Six?"
I'm going to suggest for volume measurements something on the way of the Japanese tatami mat system. In Japan, a room is measured in jo which is roughly the space needed for a sleeping mat for one adult. This comes out to just over 1.5 m^2. So I figure if you lay out the space in jo by buying a tatami mat and marking space with it, you'll come out to something which if not exact will be workable enough.