As I began using a rock climbing harness, but wanting to eventually have a more purpose built one, I recently came to an idea of how to make one, inspired by Matt Cornell's saddle. As I hope are clear enough in the pic, it's design is of a rope at the waist, which has screw links tied at either end with a tape knot. Leg loops are the rope tape knotted around the leg. The rope bridge travels through the waist rings, and connects at the leg loops by being tape knotted to screw links, which allow it to move freely. Being constructed all of knots, it will be very adjustable ! The smaller camo rope, also at the waist, is purely there as a tightener belt....it has nothing to do with the support. There are paracord ties in the back, going from the waist to the leg loops....I call them rear leg loop suspenders. The rope is the same I climb on, seeing as I bought 150 feet, and won't probably even need 100 of it anytime soon. It's Petzl's vector, 11 mm, I think. The grey foam padding, ( double layer ) is anti fatigue floor mat, from Harbor Freight.
I've only done a few short rope ascents on it, to get all adjustments dialed in. It is Lazy Boy comfy ! This particular foam is a little rubbery / grippy, so it doesn't slide over my pant legs very smoothly. I'll have to put a layer of some nylon over it. The foam at the waist and legs is a little excessively wide still, and I may trim it a little narrower. I don't know if I could describe this very well, but just as I saw in youtube vids of Matt's harness, this does allow me to smoothly rotate. I don't see any sign of the knots and screw links "interacting" in any way that could cause problems, but will be keeping a keen eye on it.
I don't have any side D's on it yet. I am not planning on using the current waist rings in this fashion only because I wonder if the pull would be more on the waist, and not pulling on the legs together.
So far so good ! Very comfy ! Cost ? I already had the rope, but if I didn't, I figured that with the amount of excess length I cut, it came to app 30 feet. $10 for the foam matt. App $6 for the screw links.