Spare morphs are pretty small; adding a 4-liter fabber, the "most common" size, like some robots have, would more than double its volume. How small is it reasonable for a specialized fabber to get? Say that I've got a Spare modified with an internal metallic-hydrogen rocket. How compact could a fabber that makes MH fuel out of available hydrogen be? What sort of tradeoffs would be involved, such as in production rate? (The specific scenario I'm imagining is a Spare being used as a courier, tootling around the solar system, containing an ego who wants to be able to travel to asteroids where there may not be a cornucopia machine available to refuel from.) Relatedly - anyone have a good idea on how expensive MH is, when bought or fabbed? (In order to work out fabrication time.) The closest I've got to clues are the mapping missile from Gatecrashing and the internal rocket from Transhuman, both with a Moderate cost, though that includes both the hardware and a load of fuel.
—Thank you for your time,