Make Your Own Cocoon Air Cleaner

What you’ll need

Core parts

• Air circulator fan (tilts to point straight up). Example used in the video: ~9" fan (≈11–12.5" outer body).
• Cotton batting, 3.5 oz/yd², enough to make a double-layer tube (“sock”).
  • Tip: this is quilting batting—look for thick, fluffy, high-loft cotton. Two layers ≈ the filtering performance of a MERV-13 furnace filter.

Tools & supplies

• Measuring tape
• Marker/pen
• Very sharp scissors
• Tape (2 kinds):
  • Low-tack tape (painter’s or masking) to hold fabric while measuring/cutting
  • Strong packing/box tape (clear plastic) for “seams”
• Thin, strong string or cord
• 2 small binder/paper clamps
• Optional: push pin, wall hook, or lamp/stand to hang the bag

Time: ~30–45 minutes the first time
Cost: often under $20–$60 depending on what you already have and where you source parts

Before you start (important)

• Work on a flat surface. Low-tack tape keeps the batting from shifting while you measure.
• Use very sharp scissors. Dull blades snag fluffy batting.
• This design assumes two layers of 3.5 oz cotton batting for the bag.
• The fan must point straight up so the bag inflates vertically (better filtration area, smaller footprint).

Step 1 — Measure your fan and calculate the bag circumference

1. Measure the outer diameter of the fan’s circular body (widest point).
   • In the video example: 12.5 in.
2. Calculate the circumference = diameter × π.
   • 12.5 × 3.14 ≈ 39.3 in.
3. Round up for overlap/seam allowance → ~40 in.

You’ll cut your batting rectangle so its short side equals this circumference (≈40") and its long side equals your target bag height (next step).

Step 2 — Decide the bag height

• The longer the bag, the more filter area and the better it cleans over time.
• A practical height (from top of the fan to where you’ll hang the bag) used in the video is ~46 in.
• Pick your target height (e.g., 40–60 in). We’ll use 46 in for the example.

Step 3 — Prep and lay out the batting (double layer)

1. Unfold your batting until you have a double layer. Keep one factory fold intact—that fold will become a strong edge.
2. Lay the double-layer sheet on the floor/table. Align it square to floorboards or a straight edge.
3. Tape the corners (and the middle if needed) with low-tack tape to keep it from creeping.

Step 4 — Mark and cut your rectangle

• Width (circumference side): 40 in (from Step 1, rounded up).
• Height (bag height): 46 in (or your chosen height).

Pro tip: Flip your tape measure so the rigid back acts like a straightedge; draw clean lines with your marker.

Cut carefully with very sharp scissors. Keep the factory fold as one of the rectangle’s four edges.

Step 5 — Reinforce all edges with packing tape

Batting edges can fray/tear. Build a strong “hem” on all four sides:

1. Lay packing tape along the edge (half on the fabric, half off).
2. Flip the piece and roll the tape over the edge so it bonds to both sides of the double-layer.
3. Repeat for all four edges (including the factory fold).
   • This creates firm edges that hold subsequent seams.

Step 6 — Form the tube (“sock”)

1. Place the rectangle flat with reinforced edges facing up.
2. Fold the left and right long edges inward until they meet in the middle (no gaps).
3. Lay a long strip of packing tape down the center, bridging both reinforced edges to join them.
4. Wrap a bit of tape around the ends of this seam to lock it in.
   • You now have a large tube (open at both ends).

Step 7 — Close the top end of the tube

1. Choose one end to be the top.
2. Flatten that end and tape it closed: lay packing tape across the opening, flip, and roll tape over so the plastic-to-plastic bond locks it firmly.
   • Plastic-to-plastic contact yields a much stronger seal than tape-to-fabric alone.

The other end remains open—that’s where the fan will go.

Step 8 — Attach the bag to the fan

Trick for easy mounting:

1. Lay the open end of the bag on the floor and fold a short cuff up to form a sturdy ring.
2. Turn the fan upside down and place it into this ring so the bag’s open edge rises up around the fan body.
3. Tape the bag’s edge to the fan housing all the way around with packing tape.
   • Work in short segments; overlap slightly so there are no gaps for leaks.

Flip the fan upright—the bag should drape up from the fan.

Step 9 — Hang the bag so it inflates straight up

• Clip two small binder clamps near the top corners/edges of the bag.
• Tie string to the clamps and tether to a push pin, wall hook, or a lamp/stand directly above.
• The fan should sit on the floor/table, pointing straight up into the bag.

Step 10 — Turn it on and check the seal

• Power on the fan (start on medium). The bag should inflate evenly.
• Feel around the fan–bag junction—no drafts/leaks should escape from the tape seam. Add tape if needed.
• You’re done—your Cocoon is filtering!

Use, care, and maintenance

• Placement: Run where you spend time (living room, bedroom). Door closed improves room cleaning.
• Run time: Continuous during smoke events; otherwise use as a 24/7 air circulator to even out room temperatures.
• Cleaning: When visibly dirty inside or airflow drops, remove the bag and gently wash (cool water, mild soap), dry thoroughly, re-mount.
• Replacement: If the batting tears, compacts, or won’t clean well, make a new bag. Cotton is biodegradable.
• Safety: Keep away from heat/flames, water, drapes. Supervise around kids/pets. Don’t block the fan’s intake.

Sizing & tweaks

• Different fan? Re-do Step 1 with your fan’s diameter. Compute circumference (diameter × 3.14), round up ~0.5–1.0 in for seam overlap.
• More performance: Make the bag taller for more surface area.
• Mounting options: Ceiling hook, wall hook, or a tall lamp/stand all work—height is adjustable via string length.
• Fun extra: If you leave the top open, you can slip the bag over a solid-top lamp and add a remote/Bluetooth bulb for a glowing “disco cocoon” while it filters.

Troubleshooting

• Bag won’t inflate: Check that the fan points straight up, verify tape seals, try a higher speed.
• Weak airflow: Bag may be clogged—wash or rebuild with fresh batting.
• Noisy/flappy bag: Shorten string so the bag is more vertical; add a light cross-tie string to keep the tube centered.
• Air leaking at the base: Retape the fan–bag junction with overlapping strips; smooth firmly.