Dena, Rick... great ideas. All I have thought of so far is adding layers of flaps by doing one set and wrapping plastic wrap around them as they dry on the wood, then doing another set right over them. When dry, the plan would be to release one set at a time. I would think you could do quite a layered look that way . There must be a lot more a person could achieve with the hinged mesh technique.... Right now -after reading Dena's post - all I can think of is wanting to make a huge goldfish with flowing thin mesh fins. I wish I was more able to sculpt a fish. Abstract shapes are easier for me (no drawing talent). Laura

Home drain/sewage pipes are commonly coated with a black slimey sludge that resembles grease. It's bacteria/bio-slime, call it what you want. It sounds like you may have it in your toilet tank, which seems odd but I'm not a plumber. I'm surprised your plumber didn't mention it as a possibility. Try cleaning the affected area with a diluted chlorine solution (maybe 4 water to 1 chlorine) plus some dishwashing detergent. Scrub the affected area and let it stay on for 15-20 minutes before rinsing off. Wear rubber gloves. See if that helps. There are also some commercial products that can be used to clean off the slime but the bleach/water/soap combo often works.

a lighter alternative I've seen used around here is the wavy fiberglass roofing material (they sell matching wavy trim stuff to make a flush edge that goes against the frame) and rigid (pink foam) insulation.

If the main issue is a home inspector gigging you for that, I'd leave it just the way it is. There are quite a few boxes that come with no hinged covers and exposed breaker toggles. It doesn't look to me like there's exposed wiring or similar hazzardous condition there, so I can't see why a home inspector would be justified in calling it a problem that must be fixed. But if you need to fix it, it might be easier to cannibalize a used box than track down the part. You can very likely find a similar used box on Ebay for pretty cheap. If so, throw away the guts, treat the cover to a can of spray paint (if necessary) and you're good to go.