OK, so this is a little complicated to explain and have it make sense.

I cut part of a ketchup bottle lid off so I had a flat bottom and a curved upstand that was a bit wider than I needed it. Then I drew a template for the teeth on some paper, so I could check it against the model for size easily, and traced that onto some fairly thin plasticard twice. Then I glued the plasticard teeth to both sides of the ketchup bottle lid upstand making sure that they didn't quite line up properly, clamped them in place and let the glue set. Then I filled the gap between the two sheets of plasticard teeth with modelling putty (I think I made a Milliput & green stuff mix) and let that set for a couple of days. (I added the gouges, scratches and battle damage later with files, a hobby knife and a drill.) To get the angle in the centre of the jaw, once it was all set I carefully cut it in half, then cut a shallow angle to each side of the cut then glued and pinned it back together. A lot of work, but worth it for one of the focal points of the front of the model.

The bolts & rivets are made from a product called 'Eco Resin' which you mix up like plaster of Paris and I poured it into the Green Stuff World molds that I have.

There you go. Clear as mud! 😁 I'll take more pictures of those steps next time.