Impressive find from an unlikely place -- well done!Or, if you want to get fancy, Amazon has a set of 4 manhole cover coasters for different cities: NYC, Chicago, Miami and LA. Amazon.com | Godinger 4 COASTERS USA CITIES MANHOLES: Stylish Coasters: Coasters
This is excellent! Right up my alley for low buck prop..
Sample pic. I don't have a done one in hand, so just imagine it as painted with a metallic paint and then weathered.
This particular lid came with Chinese food, but they come in different patterns and sizes are not standard, so you may find one more to your liking. For a manhole cover it could probably be slightly smaller, but not too much or Cap's shoulders wouldn't fit through.
Are the manholes 1/6 scale? The only ones i know are the manhole bases of the Playmates 1987 cartoon figures.Some TMNT figures did come with manhole covers, the ones I've got have 'em as stands.
You could also look into Pringles Cans, their lids maybe around the right size, though would need a lot of detailing work.