Crafts / Craftsmen / craftswomen (craftspeople, I suppose)

i seek design/fabrication help!

I've promised to make a mirror frame for a friend. she saw this design on etsy but it's £400+, and seems pretty simple to copy, but i'm umming and ahing about exactly how I'd do it.

The basic frame should be easy. It's hard to tell from the photos, but I think the original design uses bent angle iron. I wanted a 10mm 'face' but the smallest they seem to make is 13mm at 3mm thick. Instead of bending, I will instead cut and join (TIG) all four sides with mitres because I don't have anything that will bend 3mm steel cleanly. The central divider will be a simple bar. I was going to use T-section but they don't seem to make it in such slim sizes. The central bar doesn't need to hold any weight because my friend wants to mount the mirror in landscape.

The hard(er) part will be retaining the mirror glass and securing it to the wall. I've gone back and forth on a few designs, but settled on something like the below. There will be tabs on the left and right edges only and some screw-in tabs along the central strip. That way I can slide the glass in and hold it with the removable tabs. The glass will rest directly on the bottom strip, and, due to the effect of gravity, will not float upwards and burst out of the top.

I'll also use some self-adhesive felt/foam strip to cushion and protect the mirror glass. The glass is 4mm thick so there's a lot of space to take up.

For wall hanging I was just going to use holes in a couple of the glass-retaining tabs, run a regular picture cable across, and tell my friend to hang it on two chunky screws/bolts in the wall. 

My main worries are just whether the welds will hold. Any significant flaws? Anything I'm overthinking?

1 Attachment