I'd been thinking about Slash's idea of window boxes. Kept me awake last night so there I was digging through my stash at 1 AM trying to find something unusual that would work. Came up empty and gave up and went back to bed. Started this morning working on the remaining shutters; more sanding, painting, and glueing. But it's coming together nicely.
Then I got an idea. I dug out a couple of pieces of plastic fencing and started playing around with them.