We had to improvise a sery of lamps for the annual design school exhibition of 2010. We came up with an idea of a very big dôme shiny blue inside and mate black outside. But how to produce over 20 giant lamps in only 2 weeks? Here is the solution we found :
Step 1: Trash can
First, we found a big trash can. A kind of big cardboard sonotube. This seemed perfect to create a vacuum chamber.
Step 2: Hole
We inserted a tube inside the sonotube and sealed it with silicone. The tupe was was the good dimension for our shopvac. We attached them together with black tape.
Step 3: Thermoform
We heated up a 1/8 clear sheet of Polyethylene clamped in a steel frame. Of course... you need a really big oven (wich we had). The sheet was 2'X2'.
Once the sheet is just above it's melting point (the surface starts to curve), put it on the trash can. Start the vacuum and wait until the dome is formed. Make a T shape ruller to know the radius of the dome while forming.
Stop the vacuum and let it solidify.
Step 4: Hole
To create the hole on top of the lamp shade, we heated an aluminum tube with a torch during 30 seconds. Once reached the good temperature, we used it to melt a circle on top of the dome. We used IKEA suspension kits so the hole had to be 1 1/4 inch wide.
Step 5: Cut extra plastic
We clamped a Dremel to a table and used the flat surface to cut a regular edge. You will probably have to remove some extra plastic with grid 120 sandpaper.
Step 6: First layer
The first layer on the clear surface has to be the color you choosed. Use a paint that has very good covering capacity.
Step 7: Second layer
The second layer has to be while paint. This will give the glow to the color inside and patch the light holes.
Step 8: Third layer
The last layer we chose was mate black paint (or black board paint). It gives a nice contrast with the colorful and shiny inside.
Step 9: Bulb
Chose your bulb. Don't go over 60 watts. Make some tests!