Crystallon is an open source project for creating lattice structures using Rhino and Grasshopper3D. It was developed at FATHOM (www.studiofathom.com) by Aaron Porterfield (www.fequalsf.com) as an alternative to commercially available software for lattice design. The obvious advantage is the ability to generate lattice structures within Rhino’s design environment without exporting to 3rd party software, but the extended advantages include the modularity and ability to combine other powerful tools available for Grasshopper3D. The decision to release it as open source was not only to share it with the community, but to further the development through it’s users. We realize not all users will have the same applications and needs, so we hope to receive feedback and improvements from users with unique case studies. Each tool is left as a cluster which can be opened and modified at will, in the spirit of open source. We hope the community will continue to develop and contribute through the use of the Grasshopper forums and Github.