How to make a boston bag

1. Materials & tools

Materials (2 nights)

• Main fabric (8–11 oz canvas or nylon) — about 110 cm wide × 150 cm (44 × 59 in)
• Lining fabric (sheeting or nylon) — the same amount
• Heavy fusible interfacing — for the body
• Webbing for the handles (about 4 cm / 1½ in wide) — the length you chose, × 2
• Zip — about the width of the opening
• Optional: a plastic base insert

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 “Bags” → “Boston bag” from the tabs at the top.
2. Enter the size
   Enter the finished width, height, gusset, handle length and cut width, and the base corner radius. Presets cover 1 night, 2 nights and a sports size.
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. Trace the pattern
   Trace the body panels, the gusset and the handles. The gusset is a long strip — its length is the width plus twice the height.
2. Cut
   Cut two body panels and one gusset in main and lining, plus two handles. Take the gusset along the length of the fabric.
3. Apply interfacing
   Fuse heavy interfacing to the main body and gusset.

4. Sewing

4-1. Make the handles

1. Fold self-fabric handles in quarters and topstitch both edges, with webbing inside for comfort if you like.
2. For webbing handles, cut to length and seal the ends.

4-2. Attach the handles

1. Stitch a handle to each body panel, positioned symmetrically.
2. Run two lines of stitching from the handle end down about a third of the bag's height, and finish the top with a rectangle and a cross.
3. That long attachment is what stops handles pulling out. Stitched only at the top, they will come off.
4. Do this while the panels are still flat.

4-3. Attach the gusset

1. Match the center of the gusset to the center of the base of one body panel and pin.
2. Work outward from there — base, then base corners, then up the sides — pinning a little at a time.
3. Clip the gusset allowance at the base corners so it turns.
4. Attach the second body panel the same way. Assemble the lining likewise, leaving a 15 cm (6 in) gap.

4-4. Insert the zip and finish

1. Turn the main bag out and slip it inside the lining, right sides together.
2. Sandwich the zip in the opening and sew all the way around. Open the zip halfway first.
3. Turn through the gap, close it, push the lining in and topstitch around the opening.
4. Cut a plastic board to the base size and drop it in.

✏️ Always work outward from the center of the gusset. Start at one end and the two pieces run out of step, so by the far corner you are easing in several centimeters of gusset that has nowhere to go.

5. Tips & variations

• The handles are everything: a travel bag is heavy. Stitch them a third of the way down the body or they will pull out.
• Base insert: plastic board cut to the base keeps the bag flat when loaded.
• Add a shoulder strap: D-rings at each end let you add one later, which matters over any distance.