Designing for additive manufacturing is not designing without constraints, it is designing under a different set of them. Draft, undercuts and tool access disappear. Overhang angle, orientation, support access, residual stress and anisotropy arrive to replace them. A model that ignores the new list fails just as reliably as a moulded part with no draft.
Orientation is a design decision
It sets which faces carry support scarring, which features are accurate, how much support material is consumed, how tall and therefore how slow the build is, and in metal how the residual stress accumulates. Because it decides all of that, it belongs in the design conversation and on the drawing, not left to whoever loads the machine.
The self supporting angle and how to stay above it
Below a threshold angle from the build plate, an overhang needs support. Designing chamfers instead of flat overhangs, teardrop shaped horizontal holes instead of round ones, and gradual transitions instead of ledges keeps most geometry self supporting. That saves material, saves the labour of support removal, and avoids scarred surfaces where support touched.
What additive genuinely unlocks
Consolidating an assembly into one part, which removes fasteners, joints, leak paths, inspection and inventory. Internal channels that follow a surface rather than a drill path. Lattice and topology optimised structures where mass is expensive. Each of these is a redesign rather than a substitution, and a part simply printed instead of machined rarely pays.
What it adds that you must design around
Support access, because a support you cannot reach is a part you cannot finish. Anisotropy, since properties differ between and within layers. Residual stress in metal, which distorts thin and asymmetric parts. And post machining, which needs stock on accurate features and a fixturing datum somewhere on the part.
Questions people ask about design for additive manufacturing
What is design for additive manufacturing?
Designing a part around the constraints and freedoms of a layer based process: overhang angle, orientation, support access, anisotropy and post processing, rather than draft and tool access.
What is the self supporting angle?
The shallowest overhang a process can build without support. Staying above it with chamfers and teardrop holes removes support material and the labour of taking it off.
Should I just print my existing design?
Rarely worth it. Additive pays when a part is redesigned to consolidate an assembly, add internal channels, or remove mass, not when it substitutes for machining.
Does orientation belong on the drawing?
Whenever properties, accuracy or surface finish depend on it, which is most functional parts. Leaving it to the operator makes the part inconsistent between builds.