Cubic Hologram Lamp

I've always loved those little holographic bugs that museums always seemed to stock in stores, so this project was a bit of a re-imagining of that past memory. Once a friend taught me about 123D Make, I began to think of different uses of 123D Make beyond the standard stacked or slotted puzzles, and thought of making holograms. Essentially you'd have engraved acrylic stacked together to form a figure from the engravings.

I did a bit of research and most 3D holographic cubes are made from either 3D laser engravings or micro cracks made from high peak power pulses. Neither of these technologies are at my disposal so I went ahead with the 123D Make and laser cutting idea.

• acrylic (The thinner the better; you can have finer resolution of your figure since you'll have many more layers to create a cube. I used 2mm thick acrylic)
• software (I used 123D Make to slice my stl file into different layers and then Adobe Illustrator as my graphics software for separating each slice in the exported PDF. There are many other alternatives though! 123D Make is free, but it's a bit glitchy. Inkscape is also a free software with just about the same function as Illustrator)
• laser cutter (I used the Full Spectrum, hobby 20x12 at UMakers in Claremont, CA. Alternatively, you can outsource your cutting to places like Ponoko and such.)
• threaded rod and nuts (or just dowels for clamping all the pieces together)
• microfiber cloth (highly suggested) -- or kimwipes if you have access to laboratory equipment. Otherwise simple paper towels can do the job, though not too well -- I had to go with these in the end.

I could go through the steps of using 123D Make, but I already have a tutorial that gives a pretty comprehensive overview of how to use it. See my tutorial here --specifically steps 4-8 -- on making a 3D Charizard (because Pokemon Go isn't realistic enough..). (the images above are just some that I had in the tutorial; read that 'ible for more detail)

By the end of step 8 in that tutorial, you should have an exported pdf file of your hologram's slices. Read on for how to manipulate it.

Open the exported PDF in your vector graphics software of choice (mine is Adobe Illustrator, but there are free ones like Inkscape, or others like Corel Draw). Copy your pieces in order from smallest to largest in number. My 1,2,3.. up to 6 pieces were actually quite small and hard to find so I neglected them in my eventual process.

Import each piece into separate layers of a new file so that you don't get them mixed up and on the wrong layer. Each of these Illustrator layers will eventually correspond to a layer of acrylic. This means that 21-1 and 21-2 (123D Make will sometimes have multiple shapes in a layer) will be in the same layer. Make a square in the center of the artboard (use alignment tools on the top toolbar to properly align them -- click the word "align" in the top right that to see icons pop up to help you align. You want to align the square to the artboard's center so do vertical and horizontal alignment) and arrange each piece how you'd like it. To see where each piece should go relative to each other, use the 123D Make assembly steps option to see each piece's position.

For more tips and tricks, see the notes in images 6, 7, and 8 above.

Here's a quick snapshot of what my final design looked like.

Once you have each layer separated in that document, open another one for setting up each layer for cutting. It'd be inefficient to simply open each layer and cut each one separately, so we'll combine all of them into one file so you can cut in one go (and save a lot of material by arranging them into a grid).

Click the circle target looking button next to each layer (start with your smallest layer) to select all paths in that layer. Copy that (ctrl/command + C). Then paste the layer's paths into a new document and group them together so it's easier to drag later on (ctrl/command + G or right-click > group). As you add new layers, be sure to use snaps to accurately position each square side by side!

Now that you've input all your layers, you'll notice that there are darker red lines where layers' square overlap. This is because at the darker lines, there are two red lines meaning that the laser will make two passes here. You don't want that since it'll be worse on your material, so use the scissor tool to cut away one of those lines, leaving you with uniformly light colored red lines. See pictures 5 and 6 above to see what I mean.

The laser cutter I used interfaced with Retina Engrave for Full Spectrum so your layout might look different.

When you send your file over to the printer driver for your laser cutting, make sure to do some test cuts to make sure you like how the raster will look. For the 2mm acrylic that I used, raster settings were 80% power at 50% speed, and cutting was 95% power at 30% speed (for a ~40 watt laser).

I belatedly found out that the aluminum grating burns from the laser and thus scorches the acrylic, leaving nasty brown stains at the edges. Quite fitting for Charizard, but not great for holograms so I dragged the pieces to the sink to give them a bath. That worked a little but still scorching could be seen so on my next try, I removed the honeycomb supporting the material and just used wooden blocks on the edges of the acrylic. It wasn't that great for cutting since the center bowed down without support and thus the laser's focus was messed up for cutting, but it worked well in getting rid of scorch marks.

Assemble all your parts after a quick wipe down with a microfiber cloth. Work quickly so that minimal particulates get trapped between layers.

If you washed your pieces like I did after the cutting, be sure to wipe them up as quickly as you can! The water droplets will leave markings on the acrylic when dried, so avoid that by drying them up quickly.

To fasten all my layers together I had holes for a threaded bar and nuts to secure. My bar's threads were 0.133" diameter so I make my holes 0.145" diameter for clearance. Alternatively you can use specialty glue, but it's much harder to manage and ensure that no bubbles are trapped. I actually used wire through each hole to secure my layers before replacing them with the threaded bars.

To make the hologram pop even in regular light (you need to mount it on a light source or hold it up to the sun to see the full shape), I decided to another round of cutting with the rastered regions outltned in acrylic paint. Essentially, I just used a finger to gently rub in some gold acrylic paint on the rastered engravings on the acrylic before wiping it off, using a bit of water whenever necessary. Be sure that you don't let the paint dry too much! Otherwise it'll be pretty hard to remove. Also if you use water to help removing paint, make sure you don't let the water fully dry on the acrylic (hard to do when I was in LA since it was 100 degrees out) otherwise you'll be left with odd watermarks.

For display, just put it underneath some light source (I used a fairly flat button light so that it has a wide surface for light distribution) and you have an awesome holographic lamp! Or you can put it on your shelf without a lamp -- up to your discretion (plus what you have on hand).

Some options to explore in the future:

• Instead of rubbing on acrylic paint separately, try spray painting the acrylic with an even coating before rastering it away to reveal the engraving. It'd be an interesting combo of light and dark. Just a note that it might not work since you might not be able to see through your paint when you hold it up to the light, but I think it might work if you use a transparent enough paint...
• You don't have to use a cubic shape: try making polygons, or maybe icosahedrons? I'd really love to try that, actually...

Feel free to leave questions and comments below. Enjoy!