This is the Laser Guided Rubber Band Cannon that I completed recently, It is running off of an Ez-B and a 7.2v LiPo battery.
Step 1: Supplies
-1 large paper straw: from http://www.greenmunch.ca/
-1 regular paper straw from http://www.greenmunch.ca/
-1 20cm lollypop stick (optional but recommended) from http://www.greenmunch.ca/
-a decent sized flat piece of something (I used a hexagon of cardboard left over from my Hexapod Robot, 20cm in diameter)
-Rubber feet/grippers (optional but recommended)
-an elastic band
-an Ez-Robot camera from https://www.ez-robot.com/
-an Ez-B from https://www.ez-robot.com/
-at least a 5v battery
-A laser pointer (you can buy one from a dollar store)
Step 2: Tools
-An X-acto knife
-A hot glue gun
-a computer with Ez-Builder installed
Step 3: Step 1: Attach the Servos Together
Note: make sure that all of the servos are centered before starting the build.
1. Take one of your servos and screw a circular servo arm onto it.
2. Hold the first servo vertically and glue the side of the second servo to the first servo horizontally.
3. Screw a circular servo arm onto the second servo
4. Screw a bar servo arm onto the third servo at 90 degrees.
5. Glue the bottom of the third servo to the arm of the second servo at about a 45 degree angle.
Step 4: Step 2: Attach the Base
1. Glue the bottom of the first servo to the base so that the circular arm on the second servo is roughly at the center of the base.
Step 5: Step 3: Attach the Straws/barrel
1. Cut about 1cm off one of the ends of the large straw so that it makes a tiny halfpipe.
2. the casing of your third servo should be split into 3 pieces, glue the large straw to the top piece of the third servo with about 3.5cm sticking out the back. (make sure that the halfpipe is on the bottom of the straw once it is glued)
3. Glue the normal straw inside of the large straw but make sure the normal straw doesn't enter the halfpipe.
Optional- you could also glue the lollypop stick inside of the normal straw to make the barrel even stronger.
Step 6: Step 4: Add the Camera
1. glue the camera onto the third servo so that it is looking down the straw (the more parallel the straw and camera are, the more accurate your launcher will be)