I'm using SW V18 sp5 (soon to be V20!) and need to replicate this weird looking chute in sheet metal. The previous enginner who worked on this made it a thin walled extrusion and it can't be unfolded (or updated easily)

I thought I could draw the flat middle piece and join them. But honestly I can't seem to make them work without getting angled merged surface (which I don't want)

What's the right technique for making tis chute?

Thanks,

Dominic