Arc Reactor MK VI (wearable under t-shirt)

thingiverse

I built this Arc Reactor for Halloween wear. The housing is made up of two pieces, printed in PLA without supports. A custom single-layer PCB with 24 SMD LEDs (design files included), fits inside it, along with a diffuser for light (I used packaging foam). The board runs off a 5V supply (like a USB power bank). The tabs on the back take elastic up to 18mm wide. The effect works best when wearing a thin synthetic t-shirt, but still shows through a cotton one. **The USB power bank shown is just for testing and is much bigger than needed - a single-cell USB power bank like the Energizer UE2507 will provide hours of light!** Instructions: The 3D printed parts print without support (see pics). I messed up the orientation in Fusion 360, still learning... The PCB can be milled on a desktop CNC (0.3mm track/gap), and components soldered by hand (patience and flux...lots of flux). If you or your local makerspace don't have access to a desktop CNC, there are many PCB prototyping services that will manufacture this board at reasonable cost. The resistors and LEDs are 0603 size and available from reputable electronics distributors, plus places like eBay. I recommend soldering power cables directly to the board; however, if you want to place header pins, the holes have 0.1" spacing. The PCB is glued in place with hot-melt glue. I used three layers of packaging foam sheet for light diffusion, which worked well for me, but you can use whatever you like. Usually I keep packaging foam away from electronics due to ESD hazards, but in this case I wasn't concerned; my LEDs only had to last through the night (FYI the board survived and still works fine). With the PCB and diffuser material inside, the Arc Reactor housing needs to be glued shut. I used super glue (cyanoacrylate). There's no keyway between the front and back pieces, so align it carefully! I used 12mm elastic for the straps - two loops which go over my shoulders and back round under my arms. I applied silicone caulking to some of the elastic to make it non-slip, which worked great. I found that if the straps were under tension from below, there was no need for an extra strap across my back. The straps from cheap braces solved that issue, providing downward tension. I decided to put a barrel connector on the Arc Reactor so made a USB to barrel connector adapter cable. If you only plan to power it from USB, you could save time by attaching a USB cable directly to the Arc Reactor.