I, too, used the famous Build Your Own Darkroom book to construct my sink. I used fir and ply throughout and finished it with waterproof paint. Much cheaper than metal, and your saw determines all dimensions.
Mine is 41" high at the front rail and is 7" deep at the drain end. I'm 6'1" and this is just the right height for me. No fatigue, back ache or "jimmy leg"
I have built 11 darkrooms for myself and others including the university of utah and I find the best sink is 5 inches deep, 32 inches front to back, as long as possible and set the height if the rim even with your elbow to prevent bending. I injured my L-5 many years ago so I understand back pain, everything in my darkroom is tall the only problem is my children use a stool at the sink.