The Rietveld Lamp L40 was designed by Gerrit Rietveld in 1920. He used special tubular incandescent light bulbs, and built a fairly simple construction around them. Each light bulb hangs in two small wooden blocks (oak, painted black). The lamps hang from a ceiling plate, and the supply cables are led through small glass tubes.
The special light bulbs are still available (in 40 W or 60 W), but it remains to be seen for how long. In many parts of the world, the incandescent light bulbs are phased out, and will probably not be available anymore in the near future. Also, these lights are very power hungry, and not very durable. So I wanted to redesign the lamp using fluorescent lamps, but that made the construction more complex. With these lamps, a lot more wiring is required, and the tubes must be housed in a (transparent) enclosure. I made the endpieces of the enclosure of 4 mm MDF, and the transparent panels of lightly sanded acrylic glass.
For the lamps I disassembled 3 modern fluorescent lamp units, these include electronic ballasts which keep the temperature down and provide an almost instant start when power is applied. I mounted these ballasts in the ceiling plate. The ceiling plate has a ridge that is mounted over another plate with 4 angle brackets; this other plate is screwed to the ceiling. These ceiling plates are made of 12 mm MDF.
To cut out the parts of the lamp enclosure I used a laser-cutter; both 4 mm MDF and 4 mm acrylic glass can easily be cut with a low-power laser-cutter. I created a jigsaw type pattern in the MDF pieces to make sure they would glue together easily and accurately. One side of the end-pieces is not glued but bolted into place with an angle bracket, to allow for the replacement the fluorescent lamps.