You probably can, at least with the better generators.  I know that you can make colloidal copper with Utopia Silver's Silver Bullet Colloidal Generator (described in another post in this forum) by purchasing copper anodes.  I believe you can also make colloidal gold - but only if you use a high voltage system.

For more info: http://www.utopiasilver.com/products/colloidal-production-equipment/

DQ