Drawstring backpack with flap — test patterns and 3D configurator

Drawstring backpack with flap: adjustable dimensions, separate pieces, holes and PDF, SVG, DXF export. Test design for checking on a mock-up.

Drawstring backpack with flap: design example

Dimensions 260 × 320 × 120 mm estimated from a photo. Body made of two half-strips, oval bottom, flap, two separate shoulder straps and a loop handle. Holes for the drawstring Ø 6 mm. Patterns were developed independently from the shape; the drawstring fit in 3D is indicative.

Open this example in the designer

The example opens with the dimensions specified below. Its changes are saved separately from your regular work. You can return to it using the link in the editor.

Example source parameters

Linear dimensions are given in millimeters. Parameter names match the designer fields; these are the initial settings and can be changed.

Parameter	Value
Body width	260
Body height	320
Body depth	120
Flap drop	145
Strap blank	850
Strap width	30
Leather thickness	1.5
Stitch offset from edge	4
Additional seam allowance	0

Parts in this example

The dimensions below are derived from the geometric model. The parts list changes with the parameters and enabled options.

Piece	Size, mm
Front body half	308.6 × 320.0
Back body half	308.6 × 320.0
Oval bottom	260.0 × 120.0
Drawstring keeper	32.0 × 20.0
Wide backpack flap	239.2 × 277.4
Backpack strap · left	850.0 × 30.0
Strap attachment reinforcement	42.0 × 60.0
Backpack strap · Right	850.0 × 30.0
Strap attachment reinforcement	42.0 × 60.0
Loop handle	190.0 × 20.0

How the size changes the pattern piece

Calculation example: the body width parameter was changed from 260 to 286 mm. The diagram shows the Front body half piece before and after recalculation at the same scale.

Drawstring backpack with flap: Body width 260 and 286 mm — The dimensions below the drawing refer to the outer cut-edge contour. This is the result of a geometric calculation.

Open modified example

You can also download the modified JSON project. After modification, check the assembly on a mockup.

Download the pattern example

The files were generated using the standard VLOTHO CAD export from the parameters specified above. They show the model geometry and do not replace checking the product in the material.

PDF A4, 25 sheets PDF patterns, 1:1 SVG patterns, 1:1 DXF patterns, mm JSON project

PDF A4 automatically selects portrait or landscape pages and rotates the pieces to reduce the number of sheets. For assembly, a 10 mm overlap, numbers, and alignment marks are provided. The standard PDF contains one piece per page. Both variants include a 100 mm test segment. For your own dimensions, modify the project and export a new PDF. How to print patterns at 1:1 scale.

What to check before cutting

Calculated construction. Physical sewing has not been tested. First assemble a paper or inexpensive leather mock-up, then refine the fit and hardware.

VLOTHO CAD builds a geometric prototype. Allowances for bending, skiving, assembly thickness, and construction methods are determined by your material. Start with a paper mockup and a trial piece.

How to get a pattern for your dimensions

Open the model and set the dimensions in millimeters. To reproduce the tabular example, first load its JSON.
Check the parts list and enabled options. Adjust the seam and dimensions for your material.
Save the project and export a new pattern set. After changing the dimensions, the previous files no longer correspond to the project.

Dimension reference for this model: Stitching line. Dimensions in the parts table and the outer cut contour may differ due to the seam allowance. How to check seam allowances and stitching lines.

Materials and assembly

Select the leather according to the required stiffness and assembly method. The image was generated and shows the intended appearance.

File preparation

Printing patterns on A4 at 1:1 scale · DXF units and layers before cutting

Next step

Construction and export instructions · Manual contour editing · All models