Okay so finally got around to starting to get this fixed.
I bought some towing electrics 13 core wire, very thick and heavy as Doug pointed out, but quite flexible and quite cheap too £5/meter.
However I also bought some 7 core signal wire hoping it would be a little less massive, it was but less flexible £4/meter.
So I stripped the insulation off both, quite a lot of the mass resides in the insulation, especially on the 13 core cable, and set about working out what I would need in order to cover all bases, current and, as best as I can determine, projected requirements.
In the end I have made a 17 core wiring loom.
I have used the larger 2.5mm sq wire for the hotend heater, 7 amps is more than I will need at 24v (2A suffices) but then if in future heater cartridges get much more powerful, or for some unfathomable reason I go back to 12v, or I possibly consider the positive wire common, and run two negatives for dual hotends then I'm covered).
I have used larger than necessary (0.65, 0.75 mm sq wire) for some of the connections as, firstly I have it in hand, but mainly as it is well insulated, strong and flexible.
I am not currently using a filament monitor, but I have done in the past, and still have one so I have that covered. The hotend fan is not currently used, as this machine has water cooling, but I might go back to an air-cooled system later, so I have that covered too. Also I have a second thermistor which is attached to the water block, so I can directly see how effective the watercooling is. But it is a lot of cable. Here's what it looks like:
I might not need all 2 meters, but it weighs around 400g, which is not as much as I expected, and it will have keychain retractors to hold much of the weight off the effector, but it is going to contribute to lateral inertia on XY moves.
Now to get it installed. All I will say is that I can see why Canbus is quite popular these days, the idea of replacing all of this with 2 decent sized power wires, and two data cables potentially, is very appealing.
