Well, Lehle do a unit that will take a single guitar, and split it 3 ways. If you don't need simultaneous outputs (ie, you want to use the modeller or the preamp), then you can build a very simple device into a stompbox-size unit, using just a rotary switch, some wire and the connectors. If you are wanting multiple outs at the same time, then you'll need to buffer the signal to avoid loading the pickups down.