A practical framework for designing parts that are perfectly optimized for our Fused Deposition Modeling (FDM) process — stronger, more accurate, and more cost-effective to produce.
FDM builds parts layer by layer from extruded thermoplastic. That process creates considerations that simply don't exist in traditional manufacturing. Designing with FDM in mind from the start yields stronger parts, cleaner surfaces, fewer supports, and lower cost — all while preserving your design intent.
The core parameters and limits to design against for reliable, repeatable FDM parts.
Lower = finer detail, longer print
Maximum part envelope
Typical achievable accuracy
A quick pre-flight checklist before you upload. Most failed prints trace back to one of these.
Six rules that cover the vast majority of printability issues. Each shows the difference between a print-friendly design and one that fights the process.
Self-supporting angles print cleanly with no supports to remove.
Chamfer or angle overhangs to 45° or less so each layer is supported by the one beneath it.
Overhangs beyond 45° droop and need support material — adding cost, time, and post-processing.
Adequate walls guarantee strength and a fully fused surface.
Keep walls at or above 1.2 mm (about 3 nozzle widths) for solid, reliable structure.
Walls thinner than the nozzle can extrude print as gaps or fragile single lines.
Short bridges print flat without supports; long ones don't.
Keep unsupported horizontal spans under 5 mm so the extrusion stays taut between anchors.
Long bridges sag in the middle and leave drooping, stringy undersides.
Rounded transitions resist warping and crack propagation.
Add fillets or chamfers at base corners to spread stress and reduce warping.
Sharp internal corners concentrate stress and lift from the bed as the part cools.
Layer adhesion is the weakest axis — design around it.
Orient parts so working loads run along the layers (in the XY plane), the strongest direction.
Loads pulling across the layers (along Z) can split a part at the layer lines.
Teardrops self-support and hold dimensional accuracy.
Use teardrop or slightly oversized holes for horizontal bores so the top doesn't sag.
Perfect horizontal circles print with a flattened, undersized top from bridging.
Once the fundamentals are covered, these levers maximize strength, quality, and value.
Plain-language definitions for the terms used throughout this guide.
Fused Deposition Modeling — an additive process that extrudes thermoplastic material layer by layer.
The thickness of each printed layer, typically 0.1–0.3 mm. Lower means finer detail and longer prints.
The internal lattice of a part, expressed as a percentage of solid material.
Temporary structures printed to hold up overhanging features, removed after printing.
Printing an extrusion across a gap between two points with no support underneath.
A feature that extends outward at an angle greater than 45° from vertical.
Deformation caused by printed material cooling and contracting unevenly.
The vertical build direction — generally the weakest mechanical direction.
The horizontal build plane — the strongest mechanical direction for loads.
Upload your model for an instant quote with built-in DfAM analysis, or talk to our team about optimizing it first.
