Introduction: Mjolnir - With Adafruit Circuit Playground

About: tinkerer, teacher, developer, dreamer... follow me @echundotcom on twitter, instagram to see my other creations

Thor's hammer made with floor foam pads, and embedded with an Adafruit Circuit Playground so that when you start swinging or hit something, the lights on the Circuit Playground turn on and a sound plays according to a pattern of your choice. Looking to make this a Point of View light stream, so that when you swing it around and a around, the lights flash in a manner that words can be spelled, or patterns can be produced (i.e. lightning bolt) - still a work in progress with this part.


  • foam floor mats
  • x-acto knife (large)
  • rubber/contact cement
  • 3mm foam sheets
  • tube core from something like cling wrap roll
  • repurposed leather from old furniture
  • aluminum duct tape
  • Adafruit Circuit Playground
  • spray paint (silver)
  • white acrylic (or similar plastic made of translucent white - the bottom of a yogourt tub comes to mind)

Step 1: Cut and Glue Floor Foam Pads Together; Bevel the Edges

cut sections out larger than I wanted the head of the hammer to be (first attempt in green and yellow ended up too small when I beveled out the corners, so I started again with the blue and black). Using rubber/contact cement appears to be best, but make sure you're in a well ventilated area (follow instructions on how to properly adhere pieces together). Make sure to split the middle portion so that there's a channel in the middle layers.

Turns out that Mjolnir is a golden rectangle, which is awesome on so many levels.

Used a band saw to carefully cut the corners, and made sure that there was a space in between the middle so that I didn't have to cut that out afterwards.

Step 2: Wrap With Craft Foam

using 3mm craft foam, cut and glut on to the edges to smooth out the rough floor mat pattern. Form fit the pieces dry, and then using rubber/contact cement, glue the pieces on.

Step 3: Make the Handle

On the bottom, traced out the diameter of the handle, and cut around so that the handle will fit snuggly when put together (note: there's a pass through to the top of the hammer for wiring of the Circuit Playground)

Repurposing old leather from a couch that was being thrown out, cut the material to surround the handle, and then rubber/contact cement it together.

Using aluminum duct tape, cut out patters that matched Mjolnir, and the then applied across the handle, using the seam of the leather wrap as a centre point.

Made a long leather strap by folding leather in on itself and using rubber/contact cement to hold it in place... this length is longer than the hammer with the handle when folded, so that it can pass through the handle and to the top of the hammer, where it will be glued, so that when you swing the hammer by the handle, the head of the hammer does NOT fall off or fly away.

Step 4: Integrate the Adafruit Circuit Playground and Program

Attached the Adafruit Circuit Playground to the top of the hammer with the use of some velcro, and fed the wires through the head of the hammer. Cut out an area next to the handle to integrate the battery pack to power the Circuit Playground.

Using online programming tools (makecode), created code that is similar to the magic wand, so that when the hammer hits something, it starts to light up. Alternatively, you can program the Circuit Playground with Arduino, and thus have more control over the LEDs as well as the incredible sensors that are on this device.

Step 5: Paint and Finalize

Finally, crafted a surrounding wall around the Circuit Playground, as well as top made from a white acrylic sheet, which is lightly painted with the silver so that it remains translucent.

You are now worthy and have the power of Thor!

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