I posted a few days ago about my previous rivet fan being too small for some large pieces on aluminum I needed to mark. The red one shown here is good for ten holes on 3" centers; the blue one is the new one I just finished building - it's good for sixteen holes at the same spacing. It's perfect for these large pieces, but it's also easy to expand, should more be needed down the road.
Here's the real improvement, though, underneath. The hardware on the red one is just threaded into the plastic, which works but is not terribly durable; the blue one has pockets designed into it for nuts.