The coyotes are in the first railing inserts file listed on his website listed as just railing inserts, it is file #10.
Those files are listed on the site as being sized to cut at 60" wide x 36" tall, while it notes that it can be cut smaller on a waterjet or laser, I'm wondering if you had any trouble with cutting it at a smaller size on a plasma table ? I'm somewhat limited with a 2'x4' table and I've thought of purchasing some larger files from Jason @ Cascade and trying to cut them at a reduced size but I've held off so far because I didn't want to spend $70. for files that I wouldn't be able to cut with my table size.
I can't wait to see what you come up with on the homebuilt roller. I've been playing with a few ideas myself and just haven't decided on how to do it. It helps to see what others come up with when doing homebuilt projects.