Knee Pads.

I simply buy a TAR Z-Seat, cut it in half, and walla!…I have two realistic sized sit/kneeling pads that fold up nicely and fit great in my side stretch mesh pocket. Use the whole thing, or just half, whatever suits you. 2.0oz for the whole pad. It's one ounce I will always refuse to sacrifice.

http://www.rei.com/product/829881/therm-a-rest-z-seat-pad

HTH

KJ

After suffering a couple of knee injuries in the ARMY because of doing what's called a three point fall into a shooting position where you drop your knees and the butt of your rifle to the ground at the same time, I started sewing pieces of ARMY green CC foam pads into my military pants.

I would seam rip the stitching out of the top layer of the double thick knees and insert pad pieces and sew them back up with the top closure having Velcro across it so they could be removed for washing.

The hard CC foam of the ARMY sleeping pad seemed like it would be painful because it didn't compress much at all under weight, but it was an absolute savior. You had little choice of where you repeatedly dropped to your knees (lava rock, roots, sticks, river rocks, etc…).

You can buy Military style pants in a number of colors, all of which have the double knees, and a slightly softer CC foam would be more comfortable. You can occasionally even find the pants in styles with zip off legs. Check thrift stores and surplus stores to find them cheap, sometimes only a buck or two.

You can sew or glue Velcro strips onto the foam as well for use as a sit pad, cozy, tent door mat, etc…

Edit: I should also mention that you can get the pants in summer and winter weight. The summer weight has a ripstop grid pattern, and the winter weight is thicker / heavier material without the grid pattern.