Is it possible to modify a MIDI sustain pedal to for example, a guitar pedal? If so, would this be practical at all? If not, what could be an alternative use of such pedal?
Not sure what a MIDI sustain pedal is, in comparison to most other sustain pedals. But most are simple switches, working in a similar way to a doorbell push. Press the pedal, contact made, release, contact lost. There are many effects pedals that will use an extra pedal such as this, to do all sorts of different things to that effects pedal, but on its own, the only thing I can come up with is a sort of kill switch.