Whether you are a consumer, product designer or entrepreneur looking to manufacture polymer parts, one of the first decisions you will face is which 3D printing process to use. Filament based printing, most commonly known as FDM, and powder based technologies such as SLS and MJF can both deliver excellent results, but they behave very differently in terms of design freedom, performance, finish and cost.
At Midlands3D we work with all of these technologies every day, using a carefully selected range of industrial materials. This article is intended to help you decide which route makes sense for your next project and, just as importantly, when each process really comes into its own.
Understanding the processes
FDM builds parts by laying down melted thermoplastic filament layer by layer. It has been around for a long time, but modern FDM systems are a world away from the old desktop machines many people still picture. Today’s machines offer far better accuracy, repeatability and material performance, especially when run in a controlled production environment.
SLS and MJF work in a different way. Both are powder bed processes, where parts are formed by selectively fusing nylon powder. The surrounding powder supports the part as it prints, which opens up a design freedom that is difficult or impossible to achieve with filament based printing.
Materials available at Midlands3D
One of the biggest influences on process choice is material availability. On the FDM side, Midlands3D offers a wide range of engineering polymers. These include ABS and ASA for robust functional parts, polycarbonate (PC) and flame-retardant PC for applications that need higher temperature resistance, and reinforced materials such as PA6-CF and PA6-GF where stiffness and strength are critical. Flexible TPU, which is also an option in powder based printing, is also available, and is a strong option for seals, gaskets, impact absorbing components and parts that need controlled flexibility.
For powder-based printing, we focus on proven nylon materials. PA12 is a versatile workhorse with excellent strength, durability and dimensional stability, making it suitable for both functional prototypes and end use components. PA11, derived from renewable sources, offers greater flexibility and impact resistance and performs well in chemically demanding environments.
Designing for FDM versus powder bed printing
Designing for FDM requires a little more thought around orientation and support structures. Overhangs, internal channels and complex undercuts often need support material, which adds post-processing time. Layer lines are also part of the process, although modern machines and optimised print settings can produce surfaces that are far smoother than many people expect.
That said, FDM design has its advantages. Wall thicknesses are easy to control, infill can be tailored to balance strength and weight, and changes to a design can be turned around very quickly. With reinforced filaments like carbon fibre filled nylon, you can achieve excellent stiffness.
Powder based processes remove many of these constraints. Because the powder supports the part during printing, you can design complex internal features, lattice structures and snap fits without worrying about supports. This freedom makes SLS and MJF particularly attractive for intricate assemblies and consolidated parts that would otherwise require multiple components.
Mechanical and aesthetic performance
Mechanically, both approaches can deliver strong, functional parts when the right material is chosen. FDM parts tend to be strongest along the printed layers and slightly weaker between them, although this effect is far less pronounced on industrial machines. Reinforced materials and careful orientation can further improve performance.
Powder based parts have more isotropic properties, meaning strength is more consistent in all directions. This makes MJF and SLS a good fit for parts that see multi-directional loads or repeated mechanical stress.
In terms of appearance, powder based parts generally come off the machine with a more uniform, fine-grain surface. FDM parts show layer lines, but these can often be reduced through finishing or embraced as part of a functional, engineered look. For many industrial applications, aesthetics are secondary to performance and cost.
Cost and production volume
FDM has traditionally been associated with prototyping and short runs, but that perception is increasingly outdated. At Midlands3D we operate one of the largest FDM print farms in the UK, allowing us to scale production efficiently when volumes increase. With multiple machines running in parallel, FDM becomes a highly competitive option for batch production, especially for larger parts or designs that do not need the full design freedom of powder bed printing.
For one-off parts and early-stage development, FDM is often the most economical choice and offers the fastest turnaround. As volumes grow, the ability to queue and duplicate builds across a print farm keeps unit costs under control.
SLS and MJF tend to have higher entry costs for single parts, but they become very attractive for complex designs and dense batch builds where many parts can be nested into one job. For small to medium production runs that demand consistent quality and minimal finishing, powder based printing often delivers better value overall.
Finishing Options for Powder Based Prints
One of the areas where powder based printing can really shine is in the finishing options available after printing. Because MJF and SLS parts come off the machine with a slightly textured surface, investing in finishing can enhance both appearance and performance.
Midlands3D offers several in-house finishing services. DeepDye Colouring is a premium process that transforms the natural grey tone of MJF parts into a rich black, with dye penetrating the material for consistent coverage. This not only improves aesthetics but also enhances properties like heat and light resistance, making it suitable for end-use components and consumer-facing products.
PolyShot Surfacing is another step up. It uses fine media blasting to smooth and refine the exterior surface, resulting in a more uniform, polished finish. This improves tactile quality, reduces susceptibility to scratches and makes parts easier to clean.
Vapour smoothing offers an alternative route to slick, glossy surfaces. In a controlled chamber, solvent vapour lightly melts the outer surface, smoothing layer lines and minor imperfections for a sleek result that also enhances fatigue resistance and water-resistance.
These finishing steps can be crucial when your parts are going into presentation contexts, final products or environments where both appearance and durability matter.
Choosing the right approach
There is no universal answer. FDM is an excellent choice for functional prototypes, jigs and fixtures, flexible TPU components, large parts and production runs where cost efficiency and material variety matter. Modern machines, combined with industrial materials and a managed production environment, make it far more capable than many people realise.
SLS and MJF are ideal when your design is complex, mechanical performance needs to be consistent in all directions, or surface finish straight out of the machine is a priority.
Talk to the experts
The best results almost always come from matching the design, material and process from the outset. The team at Midlands3D can review your part, discuss how it will be used, and guide you toward the most suitable technology, whether that is FDM, SLS or MJF.
If you are considering your next polymer print project and want practical advice grounded in real production experience, get in touch with Midlands3D. We are here to help you move from idea to finished part with confidence.