Probably something with conductors and insulation.
Lamp-cord?
You want to pick conductor size for the MAX current. Counting quickly, #27 AWG will carry 4 Amps in total safety. You also want something that won't break. #2 won't break but won't fit in XLR, won't bend, and costs dollars a foot. Lamp-cord is way-ample for 4 Amps, voltage-drop will not be large (but you did not specify a length or drop-spec), reasonably robust underfoot, and can usually be scavenged free in your attic or town trash day.
You want insulation for 24V. A good coat of paint will do that. You also want insulation that will not flake-off in mild abuse. Plastic-coated cable comes in several toughnesses, from the wimpy stuff in my Honda to SVT heavy appliance cable. US lamp-cord is rated up to 150V from ground, exposed around your family.
The round stuff in desktop PC power cords is somewhat more abuse-tolerant than lamp-cord. I use this (or similar) for permanent connections on my basement power-monitor, where abuse-breakage could let-loose a lot more than a mere 4 Amps. But it may be a grease-fit or worse in an XLR grommet, and you already have significant power limiting. And maybe less abuse than my cellar?
Belden and enemies make a wide range of in-wall loudspeaker and elevator control cables in semi-large gauges and round jackets. But unless you read catalogs for fun, I'd just cut the tail off the nearest dead lamp or PC.
