If you use the search there was an attempt by one of the members a few weeks back. Think they copied the idea from a shops Facebook post. Unfortunately they got the pattern incorrect
The process was to make a mold, pour a product into a repair panel, fill it and bond it to the firewall pad all at the same time it appeared. Might work (if the pattern was right) to patch or repair a small area that was fairly flat but to apply the pattern across a complete, full reproduction pad with all the formed areas while retaining the pattern appears to be a challenge. Might take three of four pads before you get the technique figured out