3D Printing

This project doesn’t necessarily require 3D printing. Depending what you’re making, it may be sufficient to mount the display breakout boards on something as-is.

These little 3D-printed enclosures are useful for holding domed lenses over the displays. And they’re absolutely essential if creating something wearable. The ambient humidity in a costume will kill exposed circuit boards in no time!

We’ll start with the 3D printing because it affords the opportunity to test-fit these parts before buying the electronics, to check whether they’ll even work in the spot you have planned. They add some bulk behind the eyes and the whole idea may be a bust.

Lenses and Hardware

1.5 inch (38mm) cabochons (domes) magnify the screens slightly and give the eyes a cool 3D shape. I found mine at Tap Plastics, but any good plastics supplier should have these…or there’s eBay or Etsy. For good magnification and for the cases to hold them properly, the lenses you use should have a high dome to them…a full half-sphere.

Each enclosure requires four (4) #2-56 flat-head machine screws, 3/8" long, plus matching nuts.

This is another “probably easier to find online” part, unless you’re blessed with a well-stocked local hardware store.

3D Printables

The enclosure pieces are small and will fit even on compact entry-level printers.

There are separate versions of the enclosure for OLED vs TFT LCD…the mounting holes and cutouts are slightly different. There’s a top and bottom piece for each: for example, “LCD Top.stl” and “LCD Bottom.stl.”

I found it best to print each part as a separate job (rather than tiling all the parts on the printer bed) — less oozing / strings means less post-print cleanup — but every printer is different and maybe yours fares better in this regard.

Some filaments such as ABS are known to shrink slightly (about 2%). You may need to scale the .STL files very slightly larger before printing. DO NOT force parts into a too-small case…THEY WILL BREAK.

File or sand away any major protruberances. If you rinse off the parts afterward, make sure they’re completely dry before assembly, maybe leave them on a fan for a couple hours for good measure.

There’s a lot of variation among cabochons (lenses) from different sources, and even different batches from the same source. So it’s possible they won’t fit perfectly on the first try…

The ideal goal is for the lens to just fit in the case front, with the back faces flush. Too snug and the lens will press against the screen (possibly cracking it), too loose and it will simply fall through.

If a little too snug: use sandpaper around the opening to make it just a little wider, and try again.

If too loose: if it falls through but is a close fit, that may be good enough…we’ll glue the lens and case later.

If it’s really loose or snug, you may need to tweak the geometry to fit your specific cabochons. A CAD model for Autodesk 123D is included with the files. Use the “Press/Pull” feature to tweak this ring…positive values for a tighter fit, negative for looser…try just a fraction of a millimeter at a time. Export as STL and try again.

Assembly

Assembling the screens requires that the electronics be completed first. But since the 3D printing doesn’t apply to everyone, it’s all kept on this page rather than throughout the guide. Therefore, go ahead and work on the electronic assembly starting on the next page, and return here when you’re ready to assemble the enclosures.

Electronics should be tested and working first, then return to this page.

For each eye, you should have four major parts: a top and bottom case, a lens, and the display with ribbon cable attached. (Plus the aforementioned screws and nuts, not shown here.)

Peel off the plastic screen protector if you haven’t done this already.

The display and front piece fit together a certain way — it’s not symmetrical. A little notch provides some clearance for solder connections that tend to protrude from the front of the board (with the wires on the back).

The solder connections should be at this end of the case. NOT the thin plastic ribbon cable to the screen.

I don’t have a 3D-printed case design for the Teensy yet. If this is going inside a costume, you’ll need one, to keep out moisture.

If you’re handy with 3D CAD, it shouldn’t be too hard…a rectangle with some cutouts for wires. Otherwise, you can just get creative with a small plastic box (like some mints or breath strips come in) and hot glue. No rocket science required.

DO NOT FORCE ANYTHING. The screen glass is thin and incredibly fragile. If there is resistance during installation, stop and check tolerances, make modifications to the case as needed.

Ideally, this is how the front will go together. Board sits flush in case, dome sits flush against display…doesn’t press hard against it and doesn’t fall out.

As mentioned earlier, if it’s too tight you can sand the opening, if too loose the dome can be glued later.

A small notch on the back of the display provides clearance for the ribbon cable. (It’s slightly off-center on the OLED case, this is on purpose.) File as necessary if it doesn’t quite fit.

Fit four #2-56 nuts to the notches in the front of the case.

The notches may have some detritus from 3D printing…clean these out with tweezers or a file.

Add four #2-56 x 3/8" flat-head machine screws from the back, and tighten carefully.

If the case puts up resistance to closing, STOP. Something inside isn’t fitting right. Open the case and look for any plastic that needs filing down, or wires not sitting flat.

The display is made of glass and will break if forced.

Gluing the Lens

If the lens is loose, it needs to be glued in place. Even if it’s a good fit, gluing is a good idea for added durability! But choose wisely…

Hot glue is too clumsy and random; we need fine control. Other glues are too runny…they’ll seep into the gap and ruin the screen. Some react badly with acrylic and will make the cabochon hazy. (Cyanoacrylate glue is both too runny and causes haze…do not use it for this!)

DO NOT USE CYANOACRYLATE (“KRAZY”) GLUE.

Don’t laugh…t-shirt puff paint actually makes a decent adhesive and sealant for this project! The applicator tip lets you draw a fine bead where the case and lens meet. Just like caulking a bathtub! Allow several hours to a full day to dry completely.

You could also use this to draw a gasket between the two case pieces before closing it up, and add a bead around the hole where the wires enter. Obviously, you should test all the electronics 100% first before committing to this step.

For a more industrial bond, these same steps can be done (very carefully) with a toothpick dipped in epoxy or E6000 craft glue.

DO NOT USE CYANOACRYLATE (“KRAZY”) GLUE.

The enclosures can now be installed into something else (e.g. taxidermy dinosaur head) with your adhesive of preference…hot glue, E6000, etc. and will link up with the Teensy board as described on the “Wiring” page.

This guide was first published on Sep 07, 2015. It was last updated on Sep 07, 2015. This page (3D Printing) was last updated on Sep 16, 2019.