Here are the final few steps. Once you have created this we would love to hear how it went!

Step 5. Attach the 45 degree 2” ABS Y joint onto the arm. Duct tape it to the rigid extension piece. Then attach the barrel. We found a 36” barrel provided the fastest velocity snowball with the best maneuverability. A longer barrel gives you more velocity, but also less maneuverability. At this point you can load in a snowball into the Y joint as the backpack is on and begin your fun. Note, you will feel a solid amount of air coming out the Y joint.

Step 6. Creating the magazine. Cut a 30” piece of 2” ABS. Using a table saw, or jig saw, cut a long straight line down the ABS, leaving 1” at each end. Rotate it 1” and cut another long straight line, again leaving 1” at the end. Using a hacksaw finish off the cuts vertically so the section can be removed. Cut a 3” piece of a 1 ¾ dowel and drill a hole at towards the edge of one end. Load the dowel into the 30” piece of ABS and then insert a 1” piece of aluminum into the dowel. The plunger (dowel plus aluminum pin) should now slide up and down the magazine, but not fall out.

Step 7. It’s important to make snowballs that are exactly the right diameter. You can use a 3D printed mold we’ve made that can be ordered printed yourself or ordered online from Shapeways. Also, depending on your snow conditions, you may find that leaving the snowballs out in the below freezing weather or in the freezer for a few minutes will help them stick together.

Source: Make