Motion-activated Web Shooter with Arduino

Our giant spider thorax is ready for red flickering LED eyes and web-shooting abilities! We’re going to prototype and code a motion-activated device that will launch silly string at approaching prey …I mean trick or treaters arriving at the front door. To accomplish this, we’re using a PIR sensor with Arduino and a servo to push down the nozzle of our can of silly string every time the sensor picks up motion.

I prefer to mount the can horizontally to better hide it under the spider. That means that we’ll have to modify the nozzle to shoot from the top. Using a small drill bit I created a small hole on top of the nozzle and used hot glue to close the regular opening on the side. This worked really well except that once the can is about half empty, it begins to sputter as if it’s running out. As soon as I put the can upright again, it resumed spraying like normal so we’re going to have to mount it upright under the spider to be able to use up all the silly string in the can.