Got a strap of pretty closely matching brick from Pine Hall Brick and some mortar. Dry fit all of the brick and cleaned out the openings on Saturday, and laid the brick today. Not a pro job by any means, but a pretty solid 10-footer. Sure looks better than those awful plastic vents.
Haven't seen if the mortar color matches yet, but it should be dry in the next day or so. Did 9 of the 15 vents, and the other 6 are under low-height decks so the crawlspace people are putting covers on them.
Result.
Someone is building a house a few doors down, and I was laughing my ass off when they laid the foundation block....
...with crawlspace vents. Who builds a vented crawlspace in 2016?