All Tanked Up,
These Iperial Modelbau kits (SU-85, and SU-100) are true resins. They appear to be urethane resins, and of fair quality. The SU-100 comes as a solid super structure (fighting compartment), where as the SU-85 kit which I am currently working on is made up from several flat "slab" peices that need to be built up. The castings themselves are of pretty poor quality, they are very thick, have lots of air bubbles, and my peices are severely warped. It will take extensive work with hot water or a hair dryer to get things flat enough to glue together.

For my project I opted to stiffen the WSN chassis with a 0.80 styrene plate with structural ribs added. The lower hull is now very stiff, with virtually no flex. The upper deck will come from a Trumpeter static T-34. And I'm upgrading the stock WSN gear boxes with Tank Toko metal gears and bushings. Ethan added these to his SU-122 with good success. You can see both my Su-85 and his SU-122 build at our website at www.desertarmor.com

Craig