3D printable mini Shoji lamps
These are mini lampshades in the Shoji style that are fully 3D printable. They make use of some ancient joinery techniques to fit together like a puzzle and can be assembled with no glue or screws.
Equipment
I used a Prusa i3 MK3 for this project. You'll also want to make sure your firmware is up-to-date, and that you have the latest PrusaSlicer 2.2.0 which can insert color changes mid-print (required for the Shoji screens).
Filaments
These are the filaments I used, if you want to duplicate the look. I highly recommend you use PETG or ABS if you plan to use them outdoors. (PLA just all-around sucks, will disintegrate in the sunlight, and is a bad choice for outdoor projects. It may also not hold the joints together well.)
- 3D Universe PETG, Medium Brown. I found this Medium Brown shade to look very much like wood when viewed from a distance and if the 3D print striations are aligned correctly and with some light sanding after printing to remove the glossy sheen.
- White PETG for the back of the screens. Any white PETG will do. I have had very good results with eSun PETG in general.
- Small amount of black PETG for the "birds" and "bamboo" screens.
- Small amount of black and red PETG for the "sakura" screen.
- Small amount of black, red, grey PETG for the "fuji" screen.
Printing the roof, bars, base, and lockpins
These are all straightforward parts to print and presented no problem on my Prusa i3 MK3. The bars are the only required part for the lamp to stay together. It will hold together without the roof (although it may not look as nice), and the base is completely optional. The lockpins attach the rest of the lamp to the base, so you don't need those if you aren't printing the base.
I highly suggest you set your fill angle to 0 degrees instead of 45 degrees, so that the topmost layer will print like wood grain (in PrusaSlicer: Print Settings -> Infill -> Advanced -> Fill angle). Make sure you rotate the print to the correct orientation.
Printing the Shoji screens
| verticallines | grid | grid2 |
|---|---|---|
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| traintrack | circlemodern | fuji |
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| birds | bamboo | sakura |
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The Shoji screens require printing sequentially in multiple colors. You can do this with a single extruder setup and just change the color for different layer heights. Assuming you are using a layer height of 0.15mm, the white screen is just one single layer thick and the rest of the layers going up from there comprise the "wooden" structures (brown). Those that have drawings have them inserted at the 2nd-4th layers.
The trickiest part of printing the screens by far is making sure your bed level and Live Adjust Z is calibrated properly, since the white screen is only a single layer thick, so imperfections in your Z calibration will show. If you are using a Prusa, please use the 7x7 bed level correction mode present in more recent firmware as it works much better than 3x3.
For the color changes, use PrusaSlicer 2.2.0 or later which allows you to insert a M600 color change code in the sliced layer view. For the screens that have no drawings (i.e. no birds, bamboo, etc.), you only need white PETG (for the first layer) and one color change at the beginning of the second layer to brown PETG.
For the "birds" and "bamboo" screens you need 3 colors (first layer = white, second layer = black, third layer onwards = brown).
The "sakura" screen requires 4 colors (first layer = white, second layer = red or pink, third layer = black, fourth layer onwards = brown).
The "fuji" screen requires 5 colors (white, grey, red, black, brown in that order).
When changing the colors have some tweezers handy because the printer will often drip some filament just before it starts printing the first layer with the new color so be ready to catch that.
Assembly
The assembly of these lanterns uses puzzle joints and needs no glue or screws.
There are 3 types of bars: X, Y, and Z. Note that Y has a rounded section while X has a square section:
Begin by placing the Z bars into the roof, allowing the angled sections to lock into the cutouts. Make sure that the slots for the Shoji screen are all facing inwards. Place two Y bars (the rounded ones!) as pictured. Although not required, you may want to orient them such that the worst-looking face of your Y bar faces outward at this point, since it will eventually be rotated to not face outwards.
Now fit two X bars carefully over both the Y and Z bars, as pictured. Pay close attention to how it is in the picture. The X bar should be snap into place flush with the Z bar. Make sure it is pushed in as far as possible.
Now rotate the Y bar to lock the structure into place, being careful not to break your 3D printed parts.
Do the exact same for the bottom part of the lantern as well, and the structure should now be fairly rigid and ready to install the Shoji panels.
The Shoji panels are best inserted from the back. They should snap into place into the grooves on the Z bars. As long as you printed these in PETG or ABS they should tolerate the slight amount of flexing necessary to snap them into place.
Completed assembly.
The base can help you permanently fix the lantern to another structure. It includes two countersunk holes which you can use with M4 countersunk screws or wood screws to attach the base to another structure. The 5x5 grid of small holes is to attach custom lighting apparatus (such as a Pixie) using M2.5 self-tapping plastic screws and an adapter that you have to design.
After your base is setup with your lighting equipment and installed where you want it, set the rest of the lantern into the 4 holes for the feet, noting the direction of the triangular cutout.
Insert the lock pins from the side and you're done.
Lighting
You have multiple options for lighting. The simplest is to skip printing the base (it will hold together perfectly well without it) and just place the lamp over an electronic candle. (Don't use a real candle as your plastic is likely to melt, or worse, catch fire.) You can also make your own elaborate lighting setup -- the included base has a 5x5 grid of 10mm-spaced holes that you can use to screw in your PCB or other lighting design using M2.5 self-tapping plastic screws.
I used Adafruit Pixies which have an awkward PCB design but work extremely well for this lamp. Since my lamps are placed outdoors, I used silicone conformal coating and MR30 connectors (with a little extra E6000 to seal them) to wire together a string of the lamps that are powered from a power supply and microcontroller indoors.
