Step 1: Materials
Jacks I use 6 per system I get them from old computer mother boards. The ones I used were dual plugs one on top of the other. So I can plug in up to 6 projects at once.
.1inch perforated board ( perfboard a pretty standard electronics item )
Case for the whole thing, I had one around.
Power supply, I wired up to one that I had, a computer power supply can be useful as they often supply +12, -12, and +5 volts. There are several power supply projects on instructables, some are very good.
The cable have n wires plus a ground the ground is a shield for the other wires, I did not use it. The other wires are colored.