Resurrected, using a commercially available sling. The new Clipster3 is a great, simple safety leash.
Doing canyons, you're using ropes; from time to time you gotta clip into things. There are other products that work OK, but are heavy and expensive. Those from a climbing background often use a daisy chain, but it is awkward and long, and you don't really need the adjustability of length.
The Clipster is a canyoneering-specific clip-in sling. Made from Burly 5/8" nylon webbing, the web is first tacked into a full-strength sling, then carefully stitched together to make a nice clipper. The bottom end is girth hitched to your harness. The top end is sewn smallish to accept a 'biner, and a major-brand rubber biner-holder is provided. The 23-inch length is perfect for many canyon tasks. Some will prefer the 31-inch length.
When the length is NOT perfect, because the webbing is sewn together, you can tie it in a knot and get it untied after weighting.
Uhmm, that's about it. Pretty simple. Inspect carefully before every canyon. Retire when worn. Be careful about the rappel rope running across it while weighted. Comes in exactly one color, as shown, unless it changed. Pretty strong when brand new - but intended for body weight only.
Weight: 1.6 ounces (45 grams)