Make a Victorian Shadow Sconce

In this Instructable, I describe the construction of a 3D printed sconce that projects a Victorian wallpaper pattern on the wall.

This is an advanced project recommended only for people who are proficient with electronics and are comfortable using a soldering iron. This project can present a fire hazard if not properly executed. Proceed at your own risk!

Credits and Inspiration:

• Ornate medallion wallpaper design by Jakub Jankiewicz (kuba), public domain.
• Inspired by stereographic projection ideas of Henry Segerman and Saul Schleimer

• A 3D printer
• A DC wall adapter recycled from some discarded electronics.
• A mini 360 DC-to-DC buck converter from eBay or Amazon
• A 1W or 3W LED mounted on a 16mm round base or 20mm star base
• A bottle cap and thermal epoxy or glue
• A multimeter
• A soldering iron and rosin core solder
• Some scrap wire, some wire cutters and a wire stripper.
• Electrical tape.
• Green felt to cover up the rear of the sconce.

The power supply is a regular "wall-wart" type that comes with most electronics. Ideally you have some lying around from discarded electronics that you can use. For this project, anything between 5V and 12V should work, but make sure it puts out DC and make sure it can deliver at least three watts. Often the wattage will be written on the power supply, but if it is not, you can calculate the wattage as the product of the output voltage and the current. Here are two examples of power supplies that would work:

• A 5V power supply that puts out 1 amp would be 5 watts
• A 12V power supply that put out 0.5 amps would be 6 watts.

For your own safety, do not use a power supply larger than 12V or 2 amps!

You will also need a mini 360 DC-to-DC buck converter. This will be used to further lower the voltage into something safe for operating the LED. These are readily available on eBay or Amazon by searching for the terms "mini 360 buck converter." Use the pictures to help you identify the right one that fits in the base of the sconce.

For the sconce, you will need a 1W to 3W white LED of the type that comes mounted on either a round 16mm base or star-shaped 20mm base. In order to maximize the sharpness of the shadows, it is helpful to find an LED with the smallest die size -- something like a Cree XPE-2 might be a good choice. Searching for "XPE-2 16mm" or "XPE-2 20mm" should give you a few sources. Here is an example from eBay.

A raw LED provides some degree of cooling, but you can get more cooling with a heat-sink. I removed the rubber liner from a bottle cap with a heat gun and mounted my LED to it using thermal adhesive (the stuff they use for sticking heat sinks). This gave me additional cooling while still being low-profile enough to fit inside the sconce.

The sconce is a single plastic part. The cutouts have extremely fine details that may exceed the resolution of your printer. Even though some of the details will be filled in, the final shadow will still capture the essence of the pattern and should still look good. Don't fret the details -- all my test prints were done successfully with a consumer FDM printer at 0.2mm layer height and retraction enabled. I'm very pleased with the results!

Support is necessary for the arm but is not desired for the sconce body as it messes with the details of the cutouts. I added a brim underneath the sconce walls to prevent Cura from printing support in that region. Set "Support type" to "Touching buildplate" so that the the arm will get support but the sconce walls will not.

There are two different designs, one which projects a Victorian medallion and the other which projects a fleur-de-lis pattern.

• Cut the plug off your AC wall wart and solder the wires directly to the input pads of your DC-to-DC converter. Use a multimeter to determine which wire is positive and which is negative if you cannot tell. Polarity is very important.
• Plug in the AC wall wart and adjust the voltage on your DC-to-DC converter to a safe value such as 3V. This will keep you from blowing out your LED when you first hook it up.
• IMPORTANT: The voltage of 3V is "safe" only for white LEDs, which have a voltage drop of about 3.3V. If you want to use other color LEDs, start with about 1.5V.

Only once you have lowered the voltage on the DC converter to appropriate levels, you may proceed with this step.

• Solder wires to the LED + and - terminals. Your wires need to be long enough to reach from the front wall of the sconce, through the hole in the support arm, all the way to the DC-to-DC converter on the base. Leave a few inches of slack so you can solder the other end easily and mark the positive and negative leads.
• Feed the wires in through the inside of the sconce so they emerge from the backside.
• Solder the end of the LED wires emerging from the back of the sconce to the output terminals of the DC-to-DC converter. A set of bench top helping hands is very good for this task. Mind the polarity -- if you get it reversed, the LED will not light!

• Stick the double sided tape to the backside of the LED or bottle cap and use a marker to make a dark dot on the back of the foam-tape directly opposite the LED center.
• Positioning the LED is critical for the shadows to look correct. There is a small peep-hole on the front of the sconce to help you find the correct location.
• Look through the peep-hole as you manipulate the LED inside the cup until you see the black dot on the tape.
• Align the dot with the hole to ensure the LED is dead center and press it down to stick.

Once you first plug it in, run your sconce and monitor it to make sure the LED is not overheating. If it is, dial back the voltage on the DC-to-DC converter. You want the LED to run warm, but not hot enough to melt the plastic or cause a fire hazard. Do not run the sconce unattended until you have monitored it for several hours to make sure heat is not a problem.

Once everything is set up, mount the DC converter in the notch on the base and cover it with electrical tape. You may then cover the backside of the sconce with some felt to finish it off!