Here's two thoughts.

I haven't seen it in a while, but you could get it at electical supply houses. It's a black tape with a mild adhesive, very much like what OE's used years back. Most people think it's electrical tape, but acutally it's thinner and doesn't have adhesive that gets all gooey (especially around engine heat). After some practice you get good at spiral wrapping in a consistent pattern.

The other standby, especially for out of sight, is tie wraps every 4" or so. Kinda tedious, especially getting the wires to lay right so it doesn't look tangled/bundled. Don't use ones longer than necessary because typically the shorter they are the thinner they are, and look proprtionate. The discipline of aligning the wires and the "soldiering" of the wraps makes for a very professional look. And the wraps come in a variety of colors now, so you can play with that if so motivated. There are also "pads" made to use with these that have an adhesive back. There's a loop in the center of the pad to thread the wrap through. This way you use the same material to fasten to a side panel, or across a bulkhead.