Answer: Cable Lacing
These days, we secure our cables with Velcro straps and the ubiquitous plastic zip ties (also called cable ties). In an age before zip ties, however, cables were contained in a more organic and hand-crafted way.
How organic and hand-crafted? Although there are minor variations in cable lacing techniques across geographic regions and applications, the core of the technique is consistent. The wires are neatly bundled using spools of wax-impregnated cotton or linen string—a sort of heavy-duty dental floss, if you will. Flat lacing tapes made of modern materials such as nylon, polyester, Teflon, fiberglass, and Nomex with a variety of coatings to improve knot holding are also used sometimes now.
At set intervals along the cable bundle, the string is laced around it using a simple knot (or a combination of two types of knots in some cases). This continues for the whole length of the cable run, also being repeated whenever a new cable joins in. The finished product, even when compared to modern cable securing techniques, has a few advantages. The chances, for example, of grossly deforming or abrading the cable insulation is nearly zero and the cable lacing itself adds so little bulk to the bundle of wires that sliding the bundle through conduits is easy since there are little to no protrusions to snag on the conduit.
Amateur radio operators, electronics hobbyists, NASA engineers, and more have all used a technique known as “cable lacing” to secure permanent cable runs. When we put a man on the moon, all those hundreds of feet of cables deep within the moon lander were carefully and artfully secured with NASA’s precise cable lacing techniques.
Although the method has largely fallen out of favor, it is still practiced by NASA in specific applications (as specified in NASA Technical Standard NASA-STD-8739.4—Crimping, Interconnecting Cables, Harnesses, and Wiring). In the photo here, you can see traditional cable lacing used on the Curiosity rover on Mars. The technique has undergone something of a revival in the last few years, and a cursory internet search will turn up dozens of tutorials showing you how to lace your cables like it’s 1969.
Image courtesy of NASA.