In this guide, I will explain and show you how to make an effective carbon scrubber, using easily available and cheap materials. We will be building this filter to accommodate a 4" air duct. First lets start with our materials. TOOLS YOU WILL NEED... Scissors Flathead Scewdriver Can Opener MATERIALS YOU WILL NEED... 46 fl. OZ can of fruit juice Duct Tape Panty Hose 6"x6" Aluminum screen Container of activated carbon (pet aisle) Duct Clamp Now that we have our materials in our workspace, let's begin. We start by opening the can of juice. Pour it in another container or drink it, because you don't want to waste it. Then open the other side, rinse out, and remove the label. You should have something like this... Our next step is to cut the square of aluminum screen using our scissors. Cut the corners to make the square a circle. Once this is done, secure the screen to the bottom of the filter using duct tape. This prevents any sagging from the panty hose. The next step is to secure the panty hose to the filter using duct tape. This prevents any charcoal debris from spilling out of the filter. It should resemble this... Now, after rinsing our charcoal, we pour it into the filter. Once this is done, we can secure our filter to our exhaust vent using the duct clamp. Just place it around the device in a snug spot and tighten it with the screwdriver. Make sure it's on there good, or the filter might fall off. This filter can be produced for very cheap, less than 30 dollars. It's MUCH more effective than other scrubbers using carbon air filters. Do yourself a favor and make it as stealthy as possible... No smell, no questions. And remember to change your carbon every 3 months!