From Idea to Print-Ready Model

FDM parts are naturally weaker between layers than within a layer, so a strong design doesn't rely on the plastic being uniformly solid — it puts material where the load actually is and removes sharp features that concentrate stress.

• Fillet internal corners.

  A sharp 90° internal corner is a stress riser — cracks start there under load. A small radius spreads that stress out and can multiply the part's fatigue life.
• Use ribs instead of relying on thin cross-sections alone.

  A rib along the length of a wall resists bending far more efficiently than just making the whole wall thicker — more strength per gram of plastic.
• Thicken walls around fasteners and bosses.

  Screw bosses and snap-fit arms take repeated, concentrated force — undersized walls around them split first. Give these areas noticeably more thickness than the surrounding shell.
• Transition wall thickness gradually.

  An abrupt jump from thin to thick wall creates a weak point right at the step, and can warp as it cools unevenly. Taper between the two instead.
• Round living hinges and snap-fits generously.

  Sharp flex points fail after a handful of cycles; a generous fillet radius at the bend point lets the same feature flex thousands of times.

Most surface-quality problems trace back to a feature that's too small, too thin, or too exposed for the printing process to resolve cleanly — designing around these limits keeps the finish clean.

• Keep engraved/embossed detail above ~0.6–1 mm.

  Text or logos shallower or thinner than this blur together and lose readability — size lettering and detail with a real minimum in mind.
• Avoid walls thinner than ~0.8 mm.

  Below this they tend to print patchy, under-strength, or as pinholes rather than a clean solid surface.
• Prefer curves and fillets over sharp external edges.

  Curved surfaces hide the layer-line "staircase" effect far better than a crisp edge does, especially on visible faces.
• Keep unsupported flat spans short.

  Wide flat overhangs sag and print rough on the underside; breaking a large flat span into smaller sections keeps every part of it crisp.
• Add a small chamfer where vertical walls meet the base.

  Softens the visibility of first-layer squish ("elephant's foot") right at the bottom edge, where it's most noticeable.
• Tell us which faces are cosmetic.

  If a design has clear "show" surfaces and hidden ones, flag it in your order notes — it helps us plan support placement to protect the faces that matter.

These are the design mistakes that most often turn a cheap, quick print into an expensive, slow, or failed one.

FDM printing has real dimensional tolerance — typically around ±0.1–0.3 mm depending on the printer and material. Any two parts meant to fit together need clearance built into the design on purpose, rather than modelling both to the exact same nominal size.

Not sure which one your part needs? Tell us how the parts should behave together (permanent, occasional sliding, constant rotation, etc.) when you place your order and we'll size the clearance for you.

An overhang is any surface that extends outward without solid material directly beneath it. As a design rule of thumb, a wall angled more than about 45° from vertical starts to need help holding its own shape — beyond that angle it's worth changing the geometry itself, not just relying on the printer to support it.

How to design overhangs out:

• Chamfer instead of stepping.

  Replace a sharp horizontal ledge with a sloped 45°+ chamfer so each layer only ever oversails the one below it by a small, printable amount.
• Use teardrop or diamond holes on horizontal axes.

  A round hole printed sideways has a flat, unsupported top; a teardrop or diamond profile tapers to a point instead, so it holds its own shape as it closes in.
• Break up large flat overhangs.

  Split one wide unsupported span into a few smaller ones, or add fillets that double as permanent structural gussets rather than relying on removable support material.
• Fillet the transition from vertical to horizontal.

  A gradual curve is largely self-supporting where an abrupt 90° step is not — it turns a hard overhang into a mostly printable one.

Why it matters: unsupported overhangs sag, print stringy or rough on the underside, and can fail mid-print if they collapse. Where support is unavoidable, it adds material cost, removal labour, and leaves a visibly rougher patch where it touched the part — the same three costs covered in the sections above.