Some CAN controllers may be connected together on a single board, because they have differential inputs and outputs. Examples are the 82C200 and the SJA1000. The OP's question was about the wire. I have used untwisted hookup wire and speaker cable to make "short" networks. For installations we used specialized cables with foam dielectric, individually foil shielded, with a drain wire, and an outer braid jacket.CANbus is by definition a differential pair, essentially two wires plus ground. They generally need to be a twisted pair.
Assuming this is PIC, the PIC's CANbus implementation requires a simple CAN transceiver chip. You might think you can take the CAN Tx out of one PIC and feed it into the CAN Rx of another chip and vice versa, but no, that's impossible. Unlike the UART, the CAN protocol will not support this type of connection.
Almost anything will work for a short network. On a long network there are at least two things to watch out for.I've used some basic .35-.5mm electrical wiring for canbus in my car mate, cat5 stranded network wiring will do I should think no?
Mostly nonsense. Trunkline/dropline is a perfectly reasonable toplogy for a "long" network of say 500 meters @ 125KBaud with drops up to 3 meters. On a very short(<1Meter) network you want only a single terminator equal to the parallel combination of the terminators you would use on the long network, since reflections are no problem at all.CANbus should be wired in a line, with no "star" branch connections. And the ends must be terminated with a specified resistance to avoid causing reflections back down the bus.