take a look at this website, http://www.tmc-ltd.co.uk/commercial/saltwater-skimmers.asp
it should give you an idea as for flow rates and dimensions, you can also draw plans based on their design
you probably want to go with 14-16inch diam pvc tubing 4 to 5 ft tall for the body
i suggest you do not get clear acrylic tubing as it is $$$$ you could easily spend a 1000$ for 5 ft of 16'' diam
for your plastic needs visit http://www.usplastic.com/catalog/default.asp or http://www.ryanherco.com/
since flanges and caps for pvc this size are way overpriced (300$ + a piece) i suggest you build your own flanges from pvc sheet
i have drawn plans for a 1000gal diy skimmer piece by piece and calculated that it would cost between 1/3 and 1/2 of the price of a off the shelf model
i used to have a link how this guy made flanges for large diam. pvc pipe
if i can find it i will post it
For something like this I would forgo the protein skimmer DIY project and instead adopt an algae scrubber DIY project. See the link. For that much volume and that much feeding a skimmer would be less effective at removing nutrients than a scrubber.
seems like an interesting idea i think you would need a group of smaller panels
the thing though is that you are removing nutrients and algea so i dont know if it really serves the same function as a protein skimmer
the only thing you end up removing is the algea and what it eats nothing happens to the proteins this means you would need more frequent water chages and when youre talking about 1600g thats alot of saltmix...