Design help

[flssfabrication]

Tough question here (I think). Attached is my file that hopefully gives you the idea of what I'm after. What I have right now when its finished will be mirrored both right to left and front to back so I technically only need to design 1/4 of it. I've also debated on designing the entire left side and then mirroring it to the right. I will also attach a photo of the design I am attempting to model after. I cant figure out how to flange the top profile. Coming off of the c-channel, I need a 4x4" box that I will cut a 3" diameter hole in it for a path for exhaust. I'm struggling with ideas to design this thing. Hopefully my file and photo I have attached will help you help me. Please dont hesitate to ask questions. Thanks in advance. I am using sheet metal components so I can create flat patterns to send to a plasma table. 

[davebYYPCU · Accepted solution]

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Please avoid 3d sketching - they do not create any short cutting.

I transferred the end profile into a 2d sketch, (check flange side and profile accuracy)

and Extrude cut it to shape.

Check the time lines

[flssfabrication]

My apologies, I thought I was being clever using 3D sketch. This is very helpful and moved me forward in the process of designing this part. Thank you.