Interstellar Lamp

While thinking about what to do with this special light bulb I had the idea it will look very sci-fi like a luminated radio telescope listening for interstellar radio waves when I combine this with one of my concrete bowls, I created for candle lights in the past.

Concrete dish

• 2 Acrylic Baubles of different sizes (e.g. 20cm and 18 cm)
• reusable for other concrete projects
• Cement (DIY cement or normal one with fibre added)
• amount depends on the size of your baubles
• Water
• A Bowl
• for mixing cement and water
• Kitchen Oil
• only a little bit
• Paper towl or cotton cloth
• to apply the oil
• Disposable gloves

Base

• short piece of a wooden board
• a handsaw or a circular saw
• sanding paper or a sander
• drilling Machine with 10mm and 6mm concrete driller and a 25mm forstner dill
• 6mm bolt, nuts and washer
• optional: wood stain or black tea, hard wax oil, felt pads
• a nut driver
• a level
• one marble

For the some color

• spray paint (you decide the color or leave it plain concrete)
• metallic acrylic paint (I used bronze)
• a paint brush

For the lights

• a (vintage) lamp holder
• some lamp cable, ideally with a switch and plug
• a screw driver, a cutter
• a vintage retro industrial light bulb (long)
• I used one with amber-tinted glass (which is not that bright)

You should start with the concrete dish.

First oil your acrylic baubles with some kitchen oil. Use some paper towels or cotton cloth for this. Oil the bigger bauble on the inside and the smaller bauble on the outside.

Then put some water first into your mixing bowl and add cement until you get a smooth liquid. To estimate the amount you should aim to fill you bigger bowl by one fourth for a thin dish or by one third for a thicker one. The sickness of your dish shouldn't be more than half of your lamp holder screw length, otherwise you need get a longer screw to mount it onto your dish.

Afterwards you should fill the liquid concrete into you bigger bauble. It is easier if you put something under your bowl to prevent it from "rolling around". Then fill the smaller bauble to e.g. 90% with water and place it in the middle of your concrete. It will sink down by it's own weight. If its not enough you could place something heavier on top of it.

Then you need to wait until it is dry. This will take a few days. It is dry when the concrete looks quite brighter than before.

Now (after some days of waiting or doing other projects) pour out the water and carefully tighten the inner bauble. Rotate it and shake it slightly. Do the same with the outer bauble as well.

Now take care of the edges with some sander so they look flat and nice after.

Now you should drill the holes. One for the cable and the lamp holder mount and another one to mount it to the (wooden) base.

To find the center of the dish use a marble and a level. Put the marble in the dish, bring the dish into balance and mark the position of the marble. This should be the center of your dish. Drill here with the 10mm concrete driller.

The second hole you could place half between the center hole and the rim of the dish. Drill here with the 6mm concrete driller. This whole is to mount the dish to the base.

Try if the lamp holder screw fits into the center hole.

Now feel free to color your dish as you like. I used anthracite spray paint for the outside and the edge and painted the inside with some acrylic bronze color. Some gold color looks also great for the inside.

It's better to drill all holes first and mount the lamp stuff after. I didn't. This makes things more complicated. ;)

Find some wood board and cut it close to the dimensions of your dish. You could also use some other base, like acryl plate, steel or whatever you like, but it needs to have enough weight to hold the concrete dish (and the lamp).

So cut the wood board and sand it if you like. I painted my wood with some fresh brewed strong black tea to give it some vintage finish. You could use wood stain or leave it as it is, a you decide.

Afterwards its good to seal it with some hard wax oil.

At the end mark down the position of your mount screw. Ideally you lamp holder cable ends at the edgte of the base otherwise you need to carve your board afterwards to make it fit. Optionally you could drill a hole for your cable as well.

At the bottom of your base you should extend your hole with a forstner drill. I used a 25mm drill to give some space for the washer.

Depending on your lamp holder instruction you should thread all parts carefully in the correct order, beside the lamp sockets and then thread your lose end of your cable through the dish. If you know what you are doing with electrics, connect your cable to your lamp socket. If not, find an electrician to do this for you.

Now mount the dish with the 6mm bolt, nut and a washer on each side to your base first. It you need some space between your dish and the base (for better fit of the cable or if your screw is too long) you could place one or more nuts between dish and base. If this is not possible see my hints in step 4.

You should paint the bold head and the washer inside of the dish with the same paint you used for the inside of your dish.

At the end fasten the nut(s) of your lamp holder screw tight but not too tight (it shouldn't break the concrete).

Now screw in your light bulb and make ready for interstellar feelings ;)