I find the properties of coffee grounds fascinating (beyond the normal effects of three double espressos). Whole books have been written about the odd rheology of this soft, yet abrasive powder. I was recently playing with an evacuated foil packet of coffee and it occurred to me that it had incredible strength for its weight (caused by the particles being jammed together by the sucked-in skin of the foil).
Today’s invention exploits this property. An example application would be to create a bicycle frame using a single fattish inner tube filled with a coffee-like particulate material (and air). The cycle parts would be loosely attached to this tube to begin with so that the frame could be bent over on itself: a foldaway bicycle.
Now, straighten out the frame tube and evacuate the air (using a variant on a standard bike pump). The frame immediately can be made to rigidify…stabilising the relative positions of the wheels, bars, pedals etc enough to allow the device to be ridden away.