Really great! I continue to collect ideas for our flocks. We have 9 Runners, 4 Buffs, and a Black East Indies divided into two flocks. Long story, but one flock is a drake and two ducks.
Anyway, your setup looks like fun for the ducks!
Up here, since I have a few Runners who are not cold hardy, they sleep in the pen I built in the walkout basement. During the day in mild weather, they have a day pen - nothing exotic - but with swim pans and a nice base that is a composting straw, and they dig into it for worms and other goodies when they're not napping or swimming or eating out of their bowl.
We have just started building the new day pen - right now it's all I can do to get the basic structure up. As we go along, I entertain all kinds of ideas about what - other than a nice swim pan - goes into the day pen. I am thinking of having an A-frame shelter. The south side would be a corrugated polycarbonate, the north would be plywood painted a dark color, like a forest green. This would be their winter warm spot. In summer I could remove it, since it would not be needed. Right now winter is on my mind.
I would kind of like to set up a recirculating system for the water so it could be filtered for some water efficiency. My big wild dream would be to cycle the water through vegetable grow beds, a la aquaponics.