It would be nice to have a way to output a corresponding gear. I can make a gear with small teeth with a wide gap between them, but the same gear wouldn't really work to engage with that gear, on the other gear the teeth would need to fill the wide gap of the first gear.

As long as you keep the module and pressure angle the same, the gears should be compatible.

Only works in a one-way system, which might be okay, but if bidirectional is a requirement then the other gear would be necessary. I suppose then just create a symmetrical gear. Sorry I'm not a gear-head.