Halloween Candy Bowl

This Halloween themed project is a quick and fun introduction to the Microbit and basic laser cutting and 3D printing technologies. I created this project to keep in my office so people passing by can grab a candy and maybe a few scares.

For this project, I used a combination of the Glow forge laser cutter, and the lulzbot taz 6 3D printer. I used the glow forge to cut out the body of the grave and the tombstone. The 3D printer was used for the candy bowl and the pumpkin decorations.

As for the materials used, you will need any thin material that can fit in your laser cutter. I went with 1/8 in plywood, however you may want to use acrylic to add some extra flare. For the 3D prints, I used purple and orange PLA to keep with the Halloween theme.

The brain for this project was the BBC micro bit controller paired with the Hummingbird accessory kit. The Hummingbird kit is a revolutionary bundle that allows you to connect multiple devices to the microbit, providing ample power and an user-friendly programming platform. Through this kit I was able to connect a rotation servo motor, two RGB LEDs, and an ultrasonic sensor. 

Initially, I wanted to get an idea of what I wanted the final project to look like. The best way to do that was to sketch it out on paper. I knew I wanted it to look like a grave, so the general shape was fairly easy. After creating the design and making the body, I realized I wanted to add an ultrasonic sensor to trigger the machine. Therefore I needed a way to incorporate it naturally within the theme. I settled on adding a bat and editing it so that the eyes would be able to fit the sensor.

The base of the design is a simple box, therefore there was no intense design work needed. I utilized an online generator creator called Makerbox to create a finger jointed box to my size requirements.

I designed the tombstone using Adobe Illustrator and added some text in the middle. Before placing it in the laser cutter, I taped over the places that the text would be in order to paint it later.

I found a SVG of a bat online however, it wasn't going to work for my case. I opened it in illustrator and changed the cutout for the eyes in order to fit the ultrasonic sensor. Then I sent it to the Glowforge.

The 3D printed parts took the longest. I had to print a bowl for the candy, and some additional decoration pieces to cover the LED's.

Once all the wood pieces were cut, they needed to be painted. I painted the box black, and the tombstone with grey. I wasn't too happy with the tombstone however that is what I had on hand. To get rid of the sticky feel, I used a clear coat over everything.

a hole for the servos and the LED's.

I ran into trouble when I went to attach the tombstone to the base. Instead of cutting again, I quickly printed a simple L bracket on the Taz 6 and was able to use some super glue to get it on.

For the bat, I simply glued ut on the top corner of the tombstone and high enough that the sensor should sit flush.

The 3D prints were a bit tricky. The Pumpkins were simple to glue over the LED's, however the Attaching the bowl to the servo took some work. I ended up using one of the servo arms that came with the kit and glues it on the bottom of the bowl. I then attached it to the servo.

As a note: I left the top of the box unglued. This is simply because if I ever need to access the electronics whether it is to change bad LED, or the batteries, I would have easy access to it.

For the electronics, the hummingbird kept everything simple. It was essentially plug and play. One rotation servo in port one. Two regular LED's in ports one and two. The distance sensor in port one. and the battery pack. Thanks to the Hummingbird Kit, I was able to complete this project without the use of soldering, or breadboards.

Here is the link to my code on Microsoft Makecode. For the distance sensor, you will have to play with the values to determine which works best for you and your specific project layout. You can also change the regular LED's and replace them with the RGB LED's to get more colors.