Marina Shark Frame
 

I understand that the brand name for the Marina Shark is AMC bicycles. The
frame broke at the fold of this folding bike. I saved all of the parts. I would
like to buy a bare frame, hopefully, the identical model. How would I go about doing this. I haven't been able to contact AMC.

Talk to Marine West. Sounds like those bikes had this issue. Maybe you'll get a new bike out of it. West Marine recalls some folding bikes | Bicycle Retailer and Industry News