This holiday weekend I picked up 1/8” glass at Lowe’s which they cut to the size I needed. This is of course only for the sides as 1/8” glass is not thick enough for the top piece. Since the blade on my table saw is 1/8” I used it to cut the slots in my 1×3 frames to seat the glass.
I then was able to assemble all four sides which came together very well. When I took measurements I was slightly shocked to find that it is completely square with maybe a 1/32 of a difference.
My next move is to cut the 1×3 that will frame the top. I will be running the inside of the 1×3 frame through my router table to rabbit out a lip to hold the top glass. I may or may not also put a round over or a roman ogee edge on the outside as well.