For this year’s Halloween machine, I decided to build a robot to launch small caramel candies to the kids that come to our door. It’s a pretty simple design, with a gravity feed system, and a rubber band powered launching mechanism.

You can watch the video to get a breakdown of the design and see it in action. Continue reading for more details of the model, along with the building instructions if you would like to build it yourself.

Candies

I’m using small square creamy caramel candies pictures below, which are pretty common here in Canada, and are produced by at least a few candy manufacturers. I’m sure you can use other candies that are of similar size, basically anything around the size of two stacked 2×2 LEGO bricks. In fact, it can launch two stacked 2×2 LEGO bricks quite well, as seen in the video. I’m sure other sized candies could be used with appropriate changes to the feed system.

Instructions

The model is built from the LEGO Mindstorms Robot Inventor set (51515), so if you have that set, you will have all the pieces needed. The build should be pretty straightforward, though connecting the second motor is a bit tricky, and requires pulling the model apart slightly in order to get it connected.

Program

The program is extremely simple. It waits until something comes within range of the distance sensor (10 cm), then launches two candies by rotating the launch arms one full rotation (9 rotations of the motors). You can download the program here ( 2415caramelLauncher.lms ), or simply recreate it to match the image below.

If you use this program, you will need to connect the motors to ports A and B, and the distance sensor to port F.