I was given some concrete pavers that have scenes molded in them. I would like to paint them so that the details in each block can be seen. One is of an eagle and another is the American Flag. How do I go about doing this?
The one word answer is "Paint." If you're just going to hang them on a wall as art, then you're done.
But I'm assuming you're still going to be walking on the pavers after painting them, so it's not quite that simple and you'll need very durable outdoor paint, and/or a durable clear topcoat to protect the paint from wear & water & sun / UV damage. Perhaps:
Outdoor art paint & clear coat, this "PAINTED ROCK GARDEN MARKERS" site recommends
A deck finish like Natural Clear Transparent Waterproofing Exterior Wood Finish
"A 1-2 punch consisting of an epoxy sealer and a marine varnish" - the page says it's great for weathered wood, but it should be good over painted stone as well.
Whichever finish you choose, be sure to check that it's compatible with the paint you use.
May not be the best answer but I found using an old towel doubled over and then soaked but not dripping with paint worked well for painting the raised section, have the towel on a large garbage can liner, turn the imprinted side down and put block on the towel lift it and turn it a few degrees and put on towel check to verify there is enough paint to cover the area wanted area. Now to let it dry face up. If you want more contrast use a paint brush and a different color in the lower area after the raised area is dry this way if you have a dribble it can be quickly cleaned off. I originally painted the entire surface then when dry used the towel but had problems (my wife) thought the texture looked wrong with 2 coats of paint on the raised area but I thought it looked good and after close to 100 it is much easier to paint the whole thing then use a contrasting color with a towel on the raised area. If only doing the raised area the towel works super as it paints the slightly irregular surface quickly. This is the process we came up with hope it helps.