Geometric Construction Sets

Extensors is an extending beam based on a scissor-like mechanism.
ITSPHUN is a system of interlocking foam geometric shapes based no polygons.
PolyPuzzles are durable laser-cut paper shapes that fit together with tabs.

MathMechs Extensor(TM) Starter Set
$19.95
An extensor is an extending beam based on a scissor-like mechanism. Extensors can be connected together at nodes to build larger expanding structures. Extensors with central "Y" shaped parts have three arms in each stage, while those with "X" shaped parts have four. These build structures with different angles and geometries. The starter set contains 40 plastic parts, two springs, and a color instruction booklet. Ages 13 and up.