Or if you can find one that's close to your exact needs, use that and submit patches and pull requests upstream, or fork and maintain your fork if your changes

Or if you can find one that's close to your exact needs, use that and submit patches and pull requests upstream, or fork and maintain your fork if your changes aren't appropriate or acceptable for upstream. Easier than rolling your own if you just don't feel like going to that extreme, and still helps the ecosystem grow and thrive.