The enclosure has enough area to fit four strips of Mini Skinny NeoPixels (medium density) with 5 LEDs each to create a 5x4 matrix. Measure the strip by counting up the NeoPixels and noting where they need to separate. The strips will be installed into the LED Body1.stl part. Insert a piece of the strip and check to see if it can fit.
Cut NeoPixel Strips
NeoPixel strips are designed to be cut to create custom sized strips. Use a pair of scissors or wire cutters to cut across the three pads, being as centered as possible. We want to cut right in down the middle of the three pads. We'll need four strips with 5 LEDs each.
Lay the strips out in a 5x4 grid and orient them so the arrows are flowing from left to right. The arrows will appear in a zigzag pattern. We'll need to connect the strips together using 30AWG silicone coated wires.
Measure and cut three sets of wires (9 in total). These need to be as short as possible. Each wire for power, data and ground should have different lengths.
Use wire strippers to remove insulation from the tips of each wire. Tin the tips of the wires by appying a small amount of solder – This also helps prevent the stands of wire from fraying. Then, solder each wire to the pads on each LED strip. A pair of third helping hands can help keep the parts steady while soldering.
The Trinket, switch and battery will be housed in the LED Body2.stl part while the four NeoPixel strips will go inside the LEDBody1.stl part.
Insert the Trinket inside the LED Body2.stl part with the USB port fitting into the cutout. Now you can guage how long the connections will need to be to connect the NeoPixel strip to the Trinket. Grab a wire and measure how long it needs to be to reach the Trinket. Measure and cut three pieces of wire. Connect each wire to the three pads on the NeoPixel with the arrow point away from the wires (pointing towards the NeoPixel).
Thread wire through Hinge
Now we need to insert the three wires from the NeoPixel strip into the LED Body1.stl part. Thread the wires through the inside going out the rectangular opening on the side. Make sure the wires are straightened out to avoid them from bending while opening and closing the hinge.
Wedge the end of LED strip (with no wiring) into the LED Body1.stl part and push it all the way down inside. Hold onto the long wires from the beginning of the strip so it doesn't go inside the enclosure. Insert all four strips inside the part and stack one on top of the other. Try to have the pixels lined up with each other.
To fit the last strip, pull the wires from the end of the strip while wedging it in. Tuck the strip into the enclosure and adjust until they're fully enclosed.
You can use a flat head screwdriver or tweezers to pack the wires and sheathing into the enclosure.
Wires won't fit?
If you have trouble fitting the strips inside the enclosure, the wiring might be too long. If that's the case, you could shorten the wires and resolder to accomodate the enclosure.
Now we can fit the cover over the enclosure. The LED Top1.stl part is the long one. It snap fits on top of the LED Body1.stl part.
Now we can thread the three wires from the NeoPixel strip through the LED Body2.stl part. Insert the wires on the outside of the enclosure and through the rectangular hole. Make sure the wires and straight and twisting. Then, join the two halves together and line up the holes.
We'll use a paperclip as a pin for the hinge. Unfold a paper clip to create a long piece of solid core wire and insert it through the hole on the enclosure. Bend each end so that it can stay between both halves. We want the pin to be shorter than the length of the parts. Use wire cutters to trim the paper clip short.
Bend and Cut paperclip
Use a pair of tweezers to embed the pin into the hinge. Test opening and closing the bracelet. If the pin falls out, try bending the ends slightly so they are lodged inside the hinge.
Measure JST Extension Cable
Next, we need a way to connect the lipo battery to the Trinket and have the ability to power the circuit on and off. To do this, we'll connect a slide switch and a JST connector to the Trinket.
Grab the JST extension cable and look for the end with the female JST connector. Position the trinket, switch and connector close to one another and measure the required length needed to connect them together. Now we can gauge how long the power and ground wires need to be to connect the Trinket. The switch will be wired inline with the ground(black)wire.
Cut, strip and tin the two wires from the JST extension cable. Solder the red wire from the female JST connector to the positive pad on the back of the Trinket.
Solder Slide Switch
We'll only need two of the three leads on the slide switch. Trim the third lead (either the far left or right, but not the middle). Tin the two remaining leads with solder. Then, connect the black ground wire from the JST connector to one of the leads on the switch. We'll need a second ground wire to connect to the second lead of the switch. This new ground wire will then connect to the ground pad on the Trinket. We're essentially opening and closing the ground connection with the switch – allowing us to power the circuit on and off.
Connect NeoPixel to Trinket
Now we need to connect the three wires from the NeoPixel strip to the Trinket. The circuit fits into the enclosure best if the wires are soldered from the back of the Trinket. The data wire from the strip will connect to pin #0 on the Trinket. The positive pad from the strip connects to the BAT pin on the Trinket. Then, connect ground from the NeoPixel strip to ground on the Trinket.
Now it's time to fit the Trinket and wiring into the enclosure. Insert the Trinket into the LED Body2.stl part and orient the wires so they're straight with the back of the Tinket.
Fit JST connection
Push the wires from the JST connector tothe bottom of the enclosure. Position the JST connection facing upwards.
Fit Slide Switch
Apply pressure to the slide swith and push it between the edges of the enclosure, right next to the Trinket. Push on one side and then the other to fit the slide switch inside.
Connect the JST connector from the battery to the female connector on the Trinket. Now we can install the battery into the enclosure. Position the battery so the wires are facing towards the top. The JST connectors and battery should have enough room to easily slide inside. Wedge the excess wiring to the side and curve it long the inside of the enclosure.
Place the LED Top2.stl lid over the LED Body2.stl enclosure and press it in. If you're using the Trinket miniUSB version, you may need to cut a small part of the lid to properly attach the lid.
Snap Lid onto Trinket
The Lid has a groove that snaps onto the side of the Trinket and holds it in place. To remove the lid, use tweezers to pop it off.
Mark & Insert Magnets
Next, we'll use magnets to keep the two halves of the enclosure closed. These cylindrical magnets are diametrically magnetized so we can install them into the enclosure upright. Use a sharpie to label the matching polarities. Then, press a magnet into the indents on the edge of the enclosure halves. Ensure they're inserted with the correct matching polarities. We only need two magnets on each halve. Test the polarities of the magnets below fully embedding them. You should be able to lock the two edges together. Magnets!
And now we have an awesome NeoPixel 3D printed bracelet! Wear it over your wrist and flip the switch to try it out. When you need to recharge the battery, you can pop the cover off and disconnect the battery from the JST connector. You can use a USB Lipo charging breakout to recharge the battery over USB.
You can use these bracelets to creat stunning light paints using the long exposure photography technique.