What I don't understand is especially in unregulated box mods that already use wires and a MOSFET, why don't they include a mini-inline fuse holder? Doing that would offer short circuit protection (as long as the fuse used was at or below the max recommended discharge amp rating for the batteries used)
The trouble with traditional fuses is the time it takes them to detect an over-current condition and actually blow, and as you approach the rating of the fuse, there will be a material voltage drop across it. On a MOSFET mod, you've already got a voltage drop across the MOSFET. This can be monitored, and the MOSFET shut down if it's too high, making the fuse pretty much redundant.
For a pure mech I know this wouldn't be possible without adding wires and making not quite a pure mech.
Pure mech squonker, no wires, with fuse:
