The chip is the DNA 40 large screen...only one I like now days. The braze joint is invisible after sanding and putting a 220 grit brushed finish on the aluminum.
I use this:
Aluminum Welding Rods - Pack of 8 Low Temperature Rods and a propane/butane or map torch.
It is picky stuff to use, but after some time you get the feel of it. It is also very hard, so you want to limit the amount you have to grind off. Typically I leave the last leg long so that there is some adjustment for square and the final is a T .... join that is then sawed off and ground to a curve to match the other corners. It is also more or less essential that all the case work be done when the metal is flat.
I am still not happy with the screen cover/glass you can get with standard home tools, so I am going to use a blacked out lexan sheet for backer, then pour two part resin to fill the cavity, alleviating the need for a perfect fit on the lexan.