Step 11: Add the cardstock padding
How tall a piece you use is up to you, but you want it to cover from the left edge to the right edge of the mount. The first picture shows how I measured it without actually measuring, just line it up.
I found that folding it double and hot glueing it together made it much sturdier.
You don't want this to bend or tear in your pocket.
If you do that, it's best to glue it onto the mount with the seam side down, to keep it from catching on things.