The basic principle is this: Take a stack of packaging foam sheets, cut a hole into it, stick a light bulb in and you're done. However, one important thing is VENTILATION, which is the focus of the last step of this instructable.
I will not give precise dimensions but explain my considerations that led me to the result shown below and will enable you to built your lamp to your liking.
Please don't hesitate to contact me if you have any questions or comments.
Step 1: Materials and Tools
Packaging foam or anything you think might work:
- not too sensitive to heat.
- try to do a test whether you like the tint the light has after it has passed through it
- amount: enough to create a stack of your liking that is able to house the fixture, the bulb, some free space above the bulb and a couple of top layers.
- I got one with already a plug and a switch attached.
- It also had some screw-on ring that helped fix it to one of the foam sheets.
- a CFL light bulb works fine.
- it is imperative, that it has LOW wattage (mine has something like 15 Watts)
Some cardboard to use as a mat for cutting
ruler and pen
and an assortment of round things like cups, pans, etc to use as stencils.
Step 2: Some Considerations Before Going Ahead
Luckily this happened to work with the amount of space needed for the lamp itself, since the foam must not touch it.
Luckily the height of the stack was just enough to house the fixture, the fixing and still need enough space on top for a couple of uncut layers. My goal was to make it look like that the lamp is lit exactly from the center.
At this step don't worry about ventilation. The ventilation holes will be added in the last step.
Step 3: Hollowing Out
Then I used a cup to cut the holes in the center of the remaining sheets (image 3), except for about ten which would be the top. I actually made a stencil out of cardboard first to help me mark the position of the cup, then batch marked the sheets and then cut them one after the other.
The result can be seen in image 4 and schematically in the sectional drawing (don't worry about the vents just yet). It is important that there is some space above the lamp (in the picture it is not enough).
Step 4: Ventilation
Big mistake! The heat of the 22 Watts bulb started melting the foam almost immediately. That's when I switched it off and started thinking about ventilation.
Since the foam is such a good insulator the heat can't dissipate. Just cutting one hole will not help, either, because the air can't circulate to cool the bulb.
So I switched the lamp for a weaker one and created two vents to the hollow inner, carefully watching that it wouldn't create a direct path for the light (I am somehow obsessed with that).
You can check out the solution I came up with in the drawings. On the sectional drawing one can clearly see how the air enters at the back side through the lower vent, is heated by the lamp and then exits through the upper vent. The lower one starts at the bottom of the backside of the lamp and rises towards the bottom of the fixture (pictures 1 & 2). The outlet starts at the top of the center hole and slightly rises to the backside of the lamp (picture 3). Note how it is slightly skewed so that the light can't exit the lamp directly.
In picture 4 (sorry it's rotated) you can see the two vents at the backside, as well as in the second drawing.
Once you have visualized how the air should flow and how the vents run you can start cutting the sheets in the right order.
The ventilation now works very well. I can now leave the lamp on for however long I want.
Another suggestion: Try to keep it in a place where it doesn't get touched (since the sheets aren't attached to each other) and take care that the bulb doesn't touch the foam!
I hope you'll enjoy your lamp and will intrigue many people with it!