Most often their geometry is based on platonic solids. The simplest form is a horizontal slab of interlocking square pyramids built from aluminium or steel tubular struts. In many ways this looks like the horizontal jib of a tower crane repeated many times to make it wider. A stronger purer form is composed of interlocking tetrahedral pyramids in which all the struts have unit length. More technically this is referred to as an isotropic vector matrix or in a single unit width an octet truss. More complex variations change the lengths of the struts to curve the overall structure or may incorporate other geometrical shapes.
Space frames were independently developed by Alexander Graham Bell around 1900 and Buckminster Fuller in the 1950s. Bell's interest was primarily in using them to make rigid frames for nautical and aeronautical engineering although few if any were realised. Buckminster Fuller's focus was architectural structures and has had more lasting influence.
Space frames are an increasingly common architectural technique especially for large roof spans in modernist commercial and industrial buildings.
Notable examples of buildings based on space frames are:
Larger portable stages and lighting gantries are also frequently built from space frames and octet trusses.
Tubular space frames are also widely used in the production of modern motorcycles and automobiles (and NASCAR race cars are exclusively built from spaceframe construction), but monocoque car bodies have been more common since the 1950s. Spaceframes have also been used in the latest incarnations of the unorthodox bicycles designed by Alex Moulton.