The edge looks like it's crimped over. While it could be done, it would probably look pretty ugly after uncrimping the edge and then rolling it back over to hold the halves together.
If the media inside isn't torn up, a bath in some solvent would probably make it work as good as new as far as straining out rock and birds.
Spritzing a bit of light oil on it would help it intercept finer dust. Modern filters like K&N use that system, although they have a bit finer media. But I wouldn't trust that for running up and down dirt roads.
