He (post above) is just using the track as a straight edge for the rotary cutter. It is likely the longest straight edge he owns,
I have a 60” aluminum ruler (I was going to say “yard stick” but that sounds wrong for one that is 60” long).
I have not cut foam in ages, but when I did, a cheap electric knife (used for carving your Thanksgiving bird) works great. I’m pretty sure they can be used with any straight edge too.
For those who have not worked with leather:
Leather is quite tear resistant, but you can slice through it like a hot knife through butter (using a sharp utility knife),
Thick leather will fight back against scissors, but remains an easy victim to a sharp blade.
While on the subject of leather: Better grades of leather are vat dyed. That is they immerse the entire hide in the dye. With vat dyed leather, small cracks in the surface are the same color as the surface dye.
Cheaper grades have the dye sprayed on, and (lately) has some base coating that covers any blemishes. That is likely a thin paste made from glues and pulverized leather.
The cheapest grades of leather are called “bonded leather” and those grades are assembled like paper is. That is they make a slurry of pulverized leather and glue and then roll it out into sheets. I believe that the color is added to that slurry and when it is dried, it is ready for use.
These grades of leather were once exclusively used for leather bound books and albums, but the technology has advanced so much that cheaper grades of furniture are upholstered with bonded leather. In the past that leather would fall apart the first time you sat down on it. It is still not like natural hides, but very uniform in thickness and it makes sewing easier.