Materials
Fairly easy to find -- shop around:
However, check Didax first, as they offer a 20% discount to participants in this workshop.
pattern blocks
(available in wood or plastic.
Avoid the "foam" ones, because in my experience they are less accurately manufactured)
patty paper
plexiglas see-through mirrors (Mira, GeoMirrors, perhaps other brands)
Available from Nasco:
Geometry Labs template (template documentation: PDF)