SW 2008

I create part one (1)

Mirrored part (1), call it part (2)

Than crated part (3) that joins both parts 1&2

Part 1&2 are parallel and flat, 1” apart.

Part 3 is a half of a pipe, created by two arc’s.

This half of a pipe joins the edge of part 1&2.

I then created part (4) that just joins part 1,2&3 as one

Question;

How do I turn this into sheet metal so I can flatten it for a pattern.

I’ve used the Base tool then tried the bend tool on 1&2 where they meet 3

But all I get is errors.