FDM or resin 3D printing: which to choose for your project

Introduction

Choosing between FDM (filament) 3D printing and resin 3D printing is not a question of “quality” in general, but of final use. Some projects work perfectly in FDM and are more efficiently produced, while others benefit from resin because of detail or precision. If you are at the prototype stage or need a final part, this guide helps you make an informed choice before requesting a quote.

At Vanco Studio we work with both technologies within our 3D printing in Girona service, and the recommendation almost always comes down to three questions: what loads the part will face, what finish you need and which tolerances are critical.

What FDM 3D printing is

FDM 3D printing builds the part layer by layer by extruding plastic filament. It is a very practical technology for prototypes, functional parts and medium or large components because it offers a good balance between strength, cost and manufacturing speed.

With FDM, the result depends greatly on how the part is printed: part orientation, wall thickness, internal density and the chosen material. Layer lines are normally visible, especially on curved surfaces, although they can be optimised considerably when the design is prepared with manufacturing in mind.

What resin 3D printing is

Resin printing solidifies a liquid material using light, achieving very fine layers and a higher level of detail. That is why it is usually the option when fine finish, small lettering, delicate geometries or small parts with high definition matter.

Post-processing must also be taken into account: cleaning and curing. This step is part of the final result and can affect lead times if the project is a batch or requires a specific finish.

FDM vs Resin

DETAIL AND FINISH: FDM offers a good overall result, but layer lines are usually visible. Resin allows finer finishes and more defined detail, especially on small parts.

STRENGTH AND FUNCTIONAL USE: FDM is usually the typical choice for parts that will be used functionally (brackets, housings, adapters, replacement parts). Resin can be used for technical applications, but the appropriate resin must be selected and it is important to understand that some formulations prioritise detail over strength.

PART SIZE: FDM is more flexible for large or bulky parts. Resin is usually more efficient for small or medium parts where the detail justifies it.

PRECISION IN SMALL DETAILS: FDM can handle tolerances and fits, but resin usually wins when details are very fine.

TIME AND COST: FDM is usually more economical for volume and functional prototypes. Resin can be more cost-effective when its finish avoids later work or when detail is a requirement.

POST-PROCESSING: FDM may require sanding or adjustments if you want a visual finish. Resin always requires cleaning and curing, and sometimes careful support adjustment so the surface is perfect.

When to choose FDM and when to choose resin

Choose FDM if your priority is strength, size, optimised cost or if the part will be screwed, fitted or subjected to real use. It is common for product prototypes, brackets, housings, adapters and custom replacement parts.

Choose resin if finish, fine detail or visual precision is most important: small parts, components with delicate geometry, presentation models, parts that will be painted, or elements where small text or fine relief needs to appear sharp.

Real use cases we often see

FDM is usually a very good fit for functional parts: custom brackets, adapters, housings, guides, spacers, assembly tools or prototypes that need to be tested and corrected quickly. In these projects, the important thing is not for the surface to be “perfect”, but for the part to work and withstand use.

Resin is usually the option when the customer needs definition: small detailed parts, surfaces that need to look refined, visually precise components or models that will later be presented or finished to a higher standard.

In both cases, when the file has not been designed for printing (walls too thin, no tolerances, impossible fits), the result becomes more complicated. If you need to make the model manufacturing-ready, our graphic and 3D design service for manufacturing is there to adjust geometries, tolerances and preparation without unnecessary tests.

Common mistakes when choosing between FDM and resin

• Choosing resin for a part that will be subjected to loads or impacts simply because “it looks better”, then ending up with breakages or deformation.
• Choosing FDM for a small part with lots of detail (fine text, delicate relief) and being frustrated because it does not look sharp at that size.
• Not defining the final use: indoor/outdoor, temperature, flexing, screws, fits or friction.
• Sending a file without checking walls, tolerances and fits, and discovering the problem after it has already been printed.
• Expecting a final “product-level” finish without discussing post-processing and the required finish level.

Before printing, the most cost-effective approach is to validate the technology and material according to the part’s actual use. The same design may work in FDM or resin, but not with the same settings or the same result. If you send us the file (STL, STEP or another 3D format), approximate dimensions, quantity and final use, we can recommend the most suitable option and avoid tests that increase project cost.

If you want, we can review it with you and tell you which technology is best for your case. Write to us on WhatsApp or via contact and we will prepare it before printing.