Just got done designing mine on CAD. You learn almost as much building one to your requirement as you will brewing on it. Just Google the type of brew stand you are looking for and start drawing piping diagrams and layout to get exactly what you want.
Just bought some replacement single handle corny keg handles from these guys and o-rings. Great prices, fast responses, good selection of some hard to find home brew, wine and soda making supplies. Shipping was reasonable too.