There is no Ant-Man costume yet but the superhero persona of Henry Pym called Ant-Man is known for his ability to rapidly change size by manipulating his subatomic particles. When Pym retired, the technology was used by Scott Lang, who became the Ant-Man.
There have been rumors since 2007 that there would be an Ant-Man movie written and directed by Edgar Wright. At Comic Con in 2012, Marvel showed test footage for the projected 2014 movie.
So there’s no reason to hurry, but you should start thinking about how to make your Ant-Man costume.