if this is a one-off device, you might consider bundling your own wiring harness. not only can you get the exact mix of wire gauges you need for various purposes, but at a lot lower cost. just keep in mind, however, that if there's any environmental conditions that would require a special jacket material, you will be better off buying pre-made cable. the same goes for any shielding requirements. high voltages (above about 50 volts) requires insulation for the wires that are either thicker, or have "premium" types of insulation (like Teflon). depending on the cable length, you may need a heavier wire gauge for longer cables to minimize resistance losses (i.e. lower voltage at the other end).
cable lacing is almost a lost art. i learned how to do it when i worked for a company that made test fixtures and prototypes. i learned the NASA method which is shown here:
the other (Marline) method is shown here:
the reason we used the NASA method is that as you can tell from the pictures, if you have a loop damaged, the Marline method can unravel. the Marline method can also be problematic if you make changes to the wiring harness. the NASA method uses a clove hitch around the bundle, then a surgeon's knot to top it off. with enough practice, you can get to be almost as fast as if you were using zip ties (zip ties will always be faster but don't look as good). spacing between loops is about 1 inch
another thing to be aware of, is that with more than 3 wires in a bundle, the current capacity of the wires needs to be derated, because the wires are no longer in free air. there's a chart
[here]. this applies whether you are making the cable or buying cable.