Hey all,
First time posting here, I think....anyway, I'm the nut with the scans from the thread that Drifand posted.
I haven't run across much that ties Makoto Kobayashi to Spiral Zone except an article showcasing a full-scratch model of his in an early issue of B-Club.
It's not exactly one of the produced toys from the main toyline...it's a "real world" version of the Iron Duck walker/vehicle that was eventually made as part of the SD Spiral Zone candy toy line, Spazon Club. Hard to say definitively that it's his design but I think it's likely...
There could be more, though...Both he and Kow Yokoyama did Spiral Zone related articles for B-Club. I have a pretty complete run of the early B-club issues, but I've only seen that one article with Kobayashi's work. Kow's was actually a serialized story illustrated with photos of his models, a weird mishmash of Spiral Zone, medieval fantasy, and post-apocalyptic themes. Crazy stuff.....