This addon is available in the Concrete5 marketplace: http://www.concrete5.org/marketplace/addons/designer-content/
Designer Content is an addon for the Concrete5 CMS that provides an easy-to-use dashboard interface for generating custom block types. See the marketplace link above for a more in-depth explanation of what it's used for, as well as thorough end-user documentation (click the "Documentation" link in the sidebar).
Note that the current master branch of this repo contains a version of Designer Content that is only compatible with Concrete5.5.2 and up. If you need the older version that is compatible with 5.5.0 and 5.5.1, download the "v3.0.2" tag. If you need the older version that is compatible with 22.214.171.124 and below, download the "v2.1.3" tag.