It's time to integrate the electronics into the 3d printed frame and build the crown!
Attach the 400 mAh LiPo battery to the backpack using the JST connectors. It's going to be a tight fit, so make a little loop like the image shows.
Take the power switch and use a pair of needle nose pliers to press fit the power switch into the rectangular hole at the back of the frame.
Note: In these photos, I've used a silver slide switch with a different height and width from the Adafruit slide switch. There is a 3D file that has a hole sized for the Adafruit switch, make sure you printed that one that corresponds to the switch that you have.
Now, take both the LiPo backpack and the battery and gently push it into the case. It'll be easier to keep the switch wire on top of the battery.
Then, to keep things compact, you can loop the Trinket M0 around so that the wire makes a sort of spiral like what is shown here.
Cut some double sided tape to size, place it on the back of the Trinket M0, peel off the top layer, and gently place the Trinket M0 inside the case, with USB port side facing the hole on the side of the case, as shown.
Route the wire from the Trinket M0 to the LED strip through the slit on the inside wall of the case.
Double check that the USB port is accessible from the outside of the case. The Trinket M0 should be touching the bottom and side walls of the case.
Take the LED Strip and slide it gently from the side of the frame, LEDs facing outward and the strip hugging the inner wall.
Center the LEDs as much as possible with the holes. You'll notice that the last and first LEDs might not be as aligned with the holes as the LEDs in the center, but this will be ok as long as they stay under the laser cut pieces.
Now, with the LEDs already inside the frame, carefully tuck in each laser cut piece, aligning the laser cut hole with the 3d printed frame hole.
There should be enough friction that the laser cut pieces should stay in place, but if not then you can secure with the screws as shown in the next step.
Watch your spelling as you do this!
You can turn on the LEDs after dry-fitting all the pieces to verify that the LEDs are well-placed under each laser cut piece.
Then, secure all the pieces with m3 machine screws and bolts. I'm using gold ones here, but you can use the black nylon ones instead.
Check that the LEDs are aligned correctly by looking in the gaps between the laser cut pieces and verifying that no part of any LED is peeking through.
Tuck in more of the wire into the case to adjust the wire length while aligning.
When you've aligned the LEDs under the laser cut pieces, make sure that the exposed wire is just the right length to hug the inner wall of the crown and stay flat all along the perimeter.
Finally, carefully use some dabs of super glue to secure the wires in place. Try not to get this stuff on your fingers!
Use binder clips while the glue is drying, it should be set in a few minutes.
That's it! Turn on your lovely crown and watch your message come to life! Now the world can properly celebrate with you, and you can make someone feel incredibly special.