I have already e-mailed Damon Atchison about this but, in case there is
general interest in this material, most hardware stores sell this by
the foot as rubber matting from a roll.  It is used to protect floors,
usually 3 feet wide or wider sometimes.

If you can't find this, you might find rubber stair treads for sale
there.  It is the same type of matting.  Hope this helps.

Cheers,
Dave McPeak