My answer for a year+ old question. I needed to make a sheath for a longer blade than my current foam press would handle. I ended up using a strip of 6" x 1.5" "eZ Flex" wrestling mat that was about 5ft long. Worked great. Where to get this 1.5" "eZ Flex" wrestling mat that was about 5ft long? Well I am also a wrestling coach so I got it with a newly ordered mat as a strap pad. So you could check with local high school or college wrestling teams. Or google a supplier as request a sample of mat
Miyamoto Musashi was thought to be left handed. But there are no left handed samurai or schools of fencing in Japan. His Niten Ichi-Ryu style of two sword fighting is believed to be his adaptation of his left handedness.