I've been making pads for years and years. It's really quite simple, I'm not very crafty at all. About thirty minutes of your time and you can have a pad that will outperform most on the market.
I usually got the McDavid knee sleeve, just check your local sporting good stores to see if it can pull over your thighs.
I would go to the local tire shop and ask them for a tube. Usually some are laying around that won't hold air and you can get it for nothing.
I have found that cutting the rubber to cover the bottom half to two thirds of the neoprene works best. Additionally , usually the inner surface of the tire tube is stickier than the outer.
Glue the rubber to the neoprene with any tough multi purpose adhesive. I usually slide the neoprene over a water bottle so it's in the correct shape, glue the rubber to it then liberally tape it down with painters tape.
This will be plenty if all you are doing is basic knee barring. If you use the pad liberally for techy knee scums, I would suggest stitching the edges down. If fyiu have access to a Speedy Stitch it will take about twenty minutes and be bomber. I have also used a thick needle, pliers and dental floss.
