This is the prototype of the Tetrahedron lamp. designed by Frans van Nieuwenborg and Martijn Wegman in 1979. It is the one the designers built themselves. Only a single prototype was made.
It was shown for the first time in 1979 in an exposition in the Stedelijk Museum Amsterdam. One might call it a piece of art. After that lighting company Indoor decided to take it into production with a few alterations in the design. One might call it a lamp.
As the name "Tetrahedron" implies it has the shape of a triangular pyramid. The light bulb is held by a smaller tetrahedron shape suspended in the middle.Three glass sides of the pyramid are yet again held together by small, black tetrahedrons. (These are metal. Indoor produced them in plastic ). What makes this prototype unique is the fourth side of the pyramid: A mirror on the bottom. It repeats the whole structure with a kaleidoscopic effect. And ofcourse the light is reflected upward.
On the corners the designers labelled it with black ink; not sandblasted into the glass like the ones Indoor produced.
It is in a very good condition. The mirroring foil underneath has some damage, as the mirror is placed directly on the floor.