Iron Man Arc Reactor with a Circuit Playground Express (CPX)

This if a follow up to my previous post about how to make an Iron Man Arc Reactor with a Gemma MO, except this one details how to make it with a Circuit Playground Express. This one can be programmed with MakeCode, making it  a great project for kids! They can easily program it do different patterns, colors, play music, and turn on or off if they clap their hands.

The 3D parts where remixed from an existing project by Aelkaim. I basically modified the Crystal Bottom to hold the CPX, and Crystal Ring to hold a 24 Bit LED ring.

Print all parts at 95% scale to work with the parts I link to below. I had to do this to fit the large LED ring. If you get different parts you may need to adjust the scale. I used alligator clips to reduce the soldering and make it more kid friendly. You could just use regular wires and solder it to the CPX.

Adafruit Circuit Playground Express
24 Bit LED WS2812 Ring

3 Alligator Clips
Spray Paint (Metallic Gold, Metallic Silver,"Hammered")
Copper Wire 24 Gauge (Ace Hardware)
3 X M3 16mm screws




Download the 3D printed parts on Thingiverse

Print out these parts in Transparent or Glow in the Dark PLA
01_Crystal_Ring
02_Crystal_CPX_Bottom
04_Crystal_Top

Print out these parts in ABS (I preferred this stronger material because the PLA kept breaking when I screwed the parts together)

05_Upper_Grid
06_Lower_Grid_Caps ( Printed with a Raft to keep the tabs from breaking off when I removed them from the printer. )

Spray paint the parts your desired colors.

Cut one end off of each the alligator clips and solder the three wires on the large LED ring (V++, GND, DIN) and place it into the Crystal Ring:

Place the caps on the ring, then wrap the copper wire around the caps. Don't wrap the copper wire too thick or the lower grid will not fit later if you do.

Use the three 3M X 16mm screws to screw the Upper Lid into the Lower Grid and Crystal Top. Keep the screws flush with the backside of the Crystal top:

Connect the alligator clips from the 24 bit LED ring to the CPX. Place them on the same output as show below as the Crystal Bottom has specific cutouts for it to fit.

LED Ground > CPX Ground
LED V++ > CPX Vout
LED Di -> CPX A1.

Place the CPX in the crystal bottom. Line up the USB on one side, and pull the alligator clips through the holes on the other side. If you are using a battery, plug it in and feed those wires through a hole.

Now place the crystal bottom and CPX with the Crystal Top, Upper Grid and Lower Grid you assembled earlier.  Use some hot glue to keep it together. NOTE: YOU MAY WANT TO PROGRAM THE CPX FIRST AS YOU WILL NOT HAVE ACCESS TO THE RESET BUTTON ONCE ITS GLUED TOGETHER. SEE THE BOTTOM OF THIS POST FOR THE MAKECODE.

Place this "core" inside the LED Crystal ring. Line up the clips and the grooves in the Lower Grid and it should settle into place. Use some more hot glue to secure the "core" and the LED ring:

The USB is accessible through the hole. I was able to program mine without using the reset button by plugging/unplugging the CPX each time I wanted to load the MakeCode.

Go to MakeCode to program the CPX. Below is the code I used for the effects shown above. MakeCode makes it easy to reprogram! Add in some musical tones, or have it turn off or on when you clap your hands.