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Black Cat Chalkboard with Red and Yellow Eyes

Joe Garritano

Project by

Joe Garritano
Wayzata, USA

General Information

Scary black cat chalkboard with glowing eyes that slowly fade from yellow to red and back. Powered by an ATTiny 85 chip and rechargeable lipo battery. Charge with your phone charger! Write your own Halloween message in chalk and erase just like a chalkboard.

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Material Description Price
MDF Wood

MDF Wood

Dimensions: 12 in × 24 in, Thickness: 1/2 in


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from Inventables

File Description Unit Price


SVG of Cat Back


Download Zip

from Inventables


Carve the Kitty

5 minutes

Cut out the cat front side up in the middle of the work piece so you can flip it over to carve the pocket for the electronics.


Gently Sand off the tabs

10 minutes

I try to put the tabs on large surfaces that can easily be reached by my belt sander or palm sander. Tabs in crevices can be a nightmare.


Prime the MDF

45 minutes

Use several coats (3) of primer and after two coats, lightly sand with 220 grit or finer paper to lay the fibers flat and provide a nice glassy surface to receive the chalk board paint.


Apply 3 Coats of Chalkboard Paint

75 minutes

I did not sand between coats as this paint covers well and lays very flat.


Wire the Kitty

60 minutes

I used an At Tiny 85 microcontroller and the Tiny ISP from Sparkfun to program it just like an Arduino. The code is attached to files. These LED’s have a common ANODE which goes to the positive supply. I used 1 150ohm resistor for each LED. The code increases the analog signal on pins 0 and 1 to bring them HIGH and then LOW again. In this case, when the pin is LOW the LED is lit… see … because of the common anode.

The lipo battery was a great deal – search Amazon for PS3 controller batteries. They come in a nice plastic case.

How does it have an onboard charger? Check out for lipoly battery chargers. The battery charges when it is plugged in regardless of whether the lights are on. The lights can be on during charging. There is a red led on the charging board, visible through the hot glue – when it is on – it is charging, when it is off, the battery is fully charged.