We’re using this conduit to run wires through the van before lining the walls. This gives us a little more flexibility for the electrical systems when we install those.
£5 from Screwfix.
Update 2017-06-15: this conduit is 20mm diameter, which limits our options for routing. So we’ve also bought some 10mm conduit, which will hopefully allow for longer continuous runs.
£18 for 25m from 12V Planet