I'm about to embark on a similar project. I just finished a setter that I patterned after my 1202 but used 6 trays instead of 3 (it's 48" tall, rather than 30"). I bought a lot of the parts from Dickeys.
I bought some used hatching baskets from Hawkhead. They are 17x48. I was going to make a hatcher of those dimensions, but that seems too big, so I'm going to try to cut one and make 2, 17x24 baskets, then build the hatcher around that with 4 of the smaller baskets.
My main concern is that it is easy to clean, my current hatcher is a breeze to clean and I would really miss that if I can't get this one clean.