Jw.-I don't know the physical properties of the epoxy but you can check it out if your interested-
http://www.smooth-on.com/Model-Making/c1290/index.html
I bought all my products from them. Quick shipping and okay prices. The epoxy is plenty strong for my use. I cannot break the pads with my bare hands. This type of shovel doesn't crawl as much as an excavator or a dozer so I took that into consideration. It took me 3-4 days milling to make the master part from aluminun so machining 70-75 track pads was out of the picture and I can not do metal casting so the epoxy was the only option for me. I have not crawled the shovel in the dirt which is the true test for a model but I think it would do just fine. The way the tracks and sprockets are made I don't think dirt would bother it.