So I decided to make good use of the last day of my spring break today, and added the knotty mod to my DIY double 1.9. It's a little chilly here in PA today, but with my foam pad between the layers, my back was toasty. I'm using the pattern/template for a double layer from DIY Gear Supply. I got my ripstop with a coupon at Joann's. Amsteel, webbing and marlin spike aluminum tubes from DIY Gear Supply as well. I had enough fabric left over for a double ended stuff sack that is really more of a storage bag than a fully-compressed stuff sack. I could probably get it stuffed to half the size in the pictures, but I don't want it to get too crushed unless I'm actually out on a trip where I need to save space in a pack.
Thanks to HF members Fish and TZ Brown for some DIY advice this morning. I took your suggestions, and stopped by Joann's again for $2 worth of elastic for the Knotty mod I put in early this afternoon, as well as to Knotty himself for the idea. I had the rest of the materials on hand already.