How to Get a Replacement Plastic Part Made

Start with the part’s function

Before reproducing the shape, identify the job performed by the original component. A cosmetic cover has different requirements from a loaded hinge, pressurized fitting or heat-exposed machine component.

Record how the part attaches, what it touches, whether it flexes and what caused it to fail. This information affects geometry, material selection and whether additive manufacturing is appropriate at all.

• Where and how the part mounts
• Loads, impacts or repeated flexing
• Heat, sunlight, water or chemical exposure
• Surfaces that must align or move
• Consequences if the replacement fails

Gather the best available reference

An intact original is the most useful reference, but a broken part can still provide valuable dimensions. Save every fragment and avoid permanently gluing it together before measurements are taken, because adhesive can change critical dimensions.

Photographs from multiple directions help explain the assembly, but photographs alone do not establish accurate scale. Include the surrounding equipment and mating features so the purpose of each surface is clear.

• Original part or all available fragments
• Photos in the installed and removed positions
• Manufacturer drawings or obsolete part numbers
• Measurements of the mating assembly
• A description of what broke and when

Measure, scan or rebuild the geometry

Simple mechanical parts can often be recreated from caliper measurements and clear photographs. Critical hole spacing, shaft diameters, wall thicknesses and mating interfaces should be measured directly rather than estimated from an image.

A phone scan can provide useful reference geometry for curved or organic surfaces, but noisy mesh data rarely replaces careful measurement for precise fits. A common workflow is to use the scan as a visual reference and rebuild the functional geometry cleanly in CAD.

Choose material from the application—not the colour

The original material may not be identifiable by appearance alone. Select a replacement material according to stiffness, toughness, temperature, weather exposure and the way the component is loaded.

PLA can suit rigid indoor parts in moderate conditions. PETG is a useful general-purpose option where additional toughness and moisture resistance are helpful. ABS may suit applications needing improved heat resistance, while ASA is often considered for outdoor exposure. TPU is used when controlled flexibility is required.

Adapt the design for the manufacturing process

A direct copy is not always the best replacement. The original may have been designed for injection molding, including thin ribs, draft angles and snap features that need adjustment for another process.

A recreated part can sometimes be strengthened by changing wall thickness, adding a radius or altering its orientation. Changes must preserve mating geometry and should be evaluated against how the assembly functions.

• Use adequate wall thickness around fasteners
• Avoid sharp internal corners where stress concentrates
• Identify surfaces that require support or post-processing
• Allow realistic clearance between mating parts
• Keep critical dimensions explicit in the project notes

What to send for a useful quote

A production-ready STL is only one part of a good request. Include the quantity, intended use, material preference, colour, delivery location and any dimensions that cannot change.

• A clean, correctly scaled STL
• Photos of the original and installed assembly
• Required quantity
• Material or environmental requirements
• Critical dimensions and fit expectations
• Required delivery date