Sabine Wren Cosplay Helmet (w/ electronics and paint lines)

This was my first attempt at a helmet. I made it for my daughters' Halloween costume, because I wasn't happy with the designs I could find (including paid designs) and we really wanted a working sight with blinky lights.

I've included a STEP file of the fully assembled helmet so you can see how it all fits together and make any modifications you like. The file is sized for a child, so you'll want to scale it up 10% or so for an adult.

The sight assembly also has cutouts for an LED, wiring, magnets, and a reed switch to trigger the light when the sight is dropped into position (see below).

The LED is a 5mm RGB flasher; here's what it looked like in full costume with the sight on (the front sight cover had fallen off in this pic; I ended up gluing it on later):

Printing

The 3MF files are scaled up to fit a typical adult. They're oriented for FFF printing and should give you an idea of the appropriate support and quality settings.  A larger printer (e.g. CR-10) can handle the base helmet in one piece. Since most printers aren't big enough (e.g. Prusa MK3, Bambu X1, Ender-3) I've also split the base helmet into four parts along seams to better hide the glue joints. And I modeled in alignment features that should make it much easier to get a clean glue-up.

For portability the 3MFs use common stock printers and nozzle sizes, so these are not the exact print files that I used. In particular, I generally used bigger nozzles, larger extrusion widths, and significantly faster print speeds (but all of that will be very dependent on your specific printer and how well you have things dialed in).

The sight_screen.3mf file has settings that should get you a pretty clear screen if you use transparent PETG. There are also a bunch of tutorials on how to print clear PETG, so go with whatever works.

Assembly

I used M3 heat set inserts to hold the two ear pieces on. It's more important on the sight side, where you may need to take it apart to get at the electronics. You could also just glue the ear pieces on if you don't care about that.

The visor uses the Hobart 770580 Face Shield cut to size. No one can see your face when wearing the helmet, but according to my daughter you can still clearly see out through it, even at night.

I suggest making a paper template to fit the visor to the helmet, and then tracing that onto the face shield before cutting. There's a lot of slack space in the visor slot, so you don't have to be too accurate. Just try to leave at least a centimeter of padding around the cutouts for the helmet, and make sure to leave some extra on the bottom that you can cut flush once everything is glued in place. I used a piece of gorilla tape to hold it at the top and tacked it in place with a bit of hot melt at a few strategic spots. It held up great to quite a bit of use (including as a candy bucket).

Electronics

The electronics are really pretty simple, but it will probably involve some soldering.

The parts I used are:

• 5mm Multicolor LED Flasher
• Epoxy Encased Reed Switch w/ 2 Magnets
• CR2032 Battery case
• 22 AWG 2 Conductor Wire (Red & Black)

If you have loose LEDs without pigtails (like I did), then the first thing you need to do is solder some wires on. Make sure to leave enough slack in the wire to thread it through the stalk and route it around the inside of the helmet to the battery (40cm should be more than enough).

Next you should assemble the stalk. Sorry I don't have any pictures for this part of the assembly; it's all permanently glued together at this point. The LED fits into led_carrier.stl, which gets clamped between sight_back.stl and sight_front.stl (along with sight_screen.stl). And then sight_stalk.stl fits into the back, and the wires are are routed through it.

You'll need to glue the stalk in, and you may also have to glue the front on. I should also mention that I used leftover silver paint to make reflective surface inside the site, where the LED casts its light (this is visible in the GIF above, where the sight front had fallen off). I'm not sure if it helped, but either way the LED was very bright and visible at night.

Next you'll need to insert the magnets and reed switch. On magnet and the reed switch fit into earpiece_right.stl and the other magnet fits into the cutout in sight_stalk.stl (as shown in the picture below). The magnet in the stalk both triggers the switch and helps hold the stalk in the upright position. The reed switch must be wired inline with the LED, and can be used it to control other things (e.g. more LEDs).

The wiring inside the helmet is pretty much up to you. Since the CR2032 is so low voltage I didn't bother adding a protective resistor. I did add some extra connectors to allow me to remove the stalk or add more LEDs. The wiring itself is wedged in behind the foam padding (with some extra pieces to keep it in place). I used hot-melt glue to attach everything, including the foam and battery case.