Recycling 3D printing materials

A good post about the mater http://i.materialise.com/blog/entry/recycling-3d-printing-materials-4-possible-solutions

The article refers to four differnt methods


 * ABS- Recycling existing 3D printing materials
 * Glass-Using materials that are already recycled as 3D printing materials
 * PLA- Bioplastics
 * Recyclebot-recycling on location.