So, I've clearly failed in item #2 of my original plans. No shutters for me. I decided to give up on making the impossible possible, and cut my losses.
this peculiar item (also purchasable off Amazon, apparently, if you want one). Looks like a portable epilepsy inducer. I bought it and destroyed the item, saving some children from a cruel fate, and netted some components in the process. Turns out the covering splits in half and is the perfect size for the reservoirs. Now, to build a structure to hold the domes in place on the shield.
I sealed the open sides with a piece of plastic card sleeve, to form what looks like a terrible Diablo health icon at 70% HP. I may have put more sand than I'd like.
On the subject of painting... time to completely ruin my work by a lackluster paint job, a signature of every project I do. I used Krylon's satin finish nickel to do the outer components, and smeared a glob of horrendous red/silver mix all over the center for a metallic lavender. I made sure to use a pipe cleaner to spread some silver unevenly all over the center housing and outer rings for that extra "1st grade look", because nothing says winner like a grinning child who shat himself.