FDM or SLA resin 3D printing: how to choose

Smooth and detailed, or strong and unbreakable? We are asked often, and the honest answer is: it depends on your part. We compared the two technologies against six criteria. Precision and detail Resin wins: fine detail, clean threads, a tidy texture, where FDM leaves detail smeared and threads imprecise. Mechanical strength FDM wins: it takes impacts, vibration and repeated loads. A resin part breaks if dropped, and turns brittle over time. Heat resistance FDM wins: it holds its shape near a heat source, while resin deforms and softens. Appearance Resin wins: a smooth surface, almost injection moulded, ready to be photographed. FDM leaves visible layer lines and calls for sanding. Part size and build volume FDM wins: a large volume at a cost that stays reasonable, where resin is limited in volume and sees its price climb steeply. Cost and production runs FDM wins: economical on runs, with affordable engineering materials. Resin costs more and needs substantial post-processing, washing and UV curing. Four criteria out of six for FDM, two for resin. But neither technique wins across the board, each has its own ground. What matters most is identifying what each project actually needs: we look at your part, what it does and the constraints it faces, then choose the technique that genuinely serves your project.