I'm just planning a rack build. I have rack uprights from a 42u rack I plan to cut down to size and then I plan to use ready rails to load servers. I'm thinking 15u for this, possibly two side by side (30u total, below desk height). I am thinking of using dowels and glue as it's supposed to be strongest. Not sure yet...
I have some dimensions worked out based on having real metal uprights inside the wooden frame. Can post some notes tomorrow if it would help, I don't have to hand right now.