Hi!

Making a cone bend in sheet metal is a common problem, with many solutions presented here or at Youtube. However, none of the solutions I've found appears to solve my problem. I've attached an STL which shows the desired shape.

1. First there's a flat rectangle

2. Next is a conical bend

3. Then there's sharp bend

4. Next is large-radius bend

5. Then sharp bend

6. Finally flat, non-rectangular part

I made this starting from a flat state (i.e. sketched the flattened shape) with sketched bends, 'cause the shapes of the bends. So there was no cone but flat surface instead of it and the cone was finally done by adding a conical solid on the outer surface (and cutting from the inside)... No if I want to flatten this, I must first suppress the "conical features". The result is a nightmare which doesn't fillet properly and creates faulty STL. 

Any ideas, how to build this properly?