5 boxes of constructive triangles can cost upwards of $70, discounted.
the folks at jmj publishing
have all 5 sets of printable constructive triangles
(thanks lori from montessori for everyone [dot] com)
including a template for the boxes ( ! )
along with other dollar-saving printouts.
“The constructive triangles are used to demonstrate that all plane geometric figures can be constructed from triangles. There are five boxes: 2 rectangular, 1 triangular, and 1 large and 1 small hexagonal. Each box contains triangles of different sizes, shapes, and colors. With the exception of Rectangular Box 2, black guidelines are painted in different positions on the triangles to help the child to construct other figures. This should be encouraged as an exploratory work that will provide a foundation for later concepts of equivalency, similarity, and congruency.” (http://www.montessoriworld.org/sensfile/sconstr.html)