How to make a water bottle cover

1. Materials & tools

Materials (600 ml standard)

• Main fabric (oxford, quilted cotton or canvas) — about 60 × 50 cm (24 × 20 in)
• Lining fabric (insulating sheet, or lightweight quilted cotton) — the same amount
• Webbing or a self-fabric strap — the length you chose
• A slider and swivel hook for adjustment — 1 each
• Snap fastener for the lid — 1 set

Tools

• Sewing machine (or needle and thread)
• Fabric marker or pencil
• Ruler and scissors
• Iron
• Pins or clips

2. Make the pattern (auto-generated in Katagami)

With the Katagami pattern tool, you just enter the finished size and it drafts a seam-allowance-included pattern, tiled to print at actual size on Letter or A4.

1. Open the tool
   Open the pattern tool and choose “Accessories” → “Water bottle cover” from the tabs at the top.
2. Enter the size
   Enter the flask diameter and height, the strap length and cut width. Presets cover a 480 ml child flask, 600 ml standard and 1 L.
3. Set the seam allowance
   Use the slider at the bottom (beginners: 1.0–1.5 cm / about 3/8–5/8 in).
4. Print
   Press “Print (actual size)”, then in the print dialog set Scale = 100% and turn “Fit to page” OFF. Check the 50 mm calibration box on the first guide sheet with a ruler.

3. Cutting the fabric

1. Measure the flask
   Measure the widest diameter and the height including the cap and handle. Measuring the body only gives a cover the flask will not fit into.
2. Trace the pattern
   Trace the base (circle), the body, the lid (circle) and the strap. Trace the circles accurately.
3. Cut
   Cut the base, body and lid in both main and lining, and one strap.

4. Sewing

4-1. Make the strap and lid

1. For a self-fabric strap, fold in quarters, press and topstitch. For webbing, cut to length and seal the ends.
2. Sew the lid main and lining right sides together, leaving the straight attachment edge open.
3. Clip the curve, turn, press and topstitch around.

4-2. Sew the body into a tube

1. Fold the main body right sides together and sew the short edge. Press the seam open.
2. Do the same with the lining, leaving an 8 cm (3 in) gap for turning.

4-3. Attach the base

1. Pin the base circle to the lower edge of the tube, right sides together, pinning at four points first.
2. Sew with the circle uppermost, turning the work gradually and clipping the allowance every 5 mm.
3. Attach the lining base the same way.

4-4. Join and add the snap

1. Turn the main piece out and slip it inside the lining, right sides together.
2. Catch the lid at the back edge and the strap ends at the sides, then sew around the opening.
3. Turn through the gap, close it, push the lining in and topstitch around the opening.
4. Put the flask in, close the lid and fit the snap 2–3 mm outside where it lands, to allow for the thickness.

✏️ Setting the circular base into the tube is the only awkward part. Pin at four points and halve the gaps from there. If the circle seems slightly off, add pins rather than pulling — pulling distorts the base and the flask goes in crooked.

5. Tips & variations

• Insulating sheet: sold as thermal or foil-backed sheeting in craft shops. The difference is genuinely noticeable.
• Measure with the cap on: flask height means the whole thing, lid and handle included.
• Adjustable strap: children grow. A slider makes the cover last several years.