How Do I Make a Flanged Box With All Edges Mated Together?

I am designing a part that needs to provide a vacuum seal around its perimeter (i.e. there cannot be any leak paths) and am having trouble finding a suitable way of joining the edges of my part (see images and attached SW part).  Ultimately all of the edges will be welded together to provide the seal, but I need to get the edges closer than they are now before it's even ready to be welded (look at the second image showing the close up of one set of edges, there's still a gap; I'd like for those inside edges to be touching).  I have created a single flat base flange, and then used sketched bends (8 plcs) to create the part in the images below.  Is there a more efficient way to do this, considering I want the final configuration to have edges that tough one another?

SolidworksSheet Metal