Choosing between SLA and SLS is less about naming a better plastic 3D printing process and more about defining what the next prototype must prove. A medical-device team may need a smooth model for an access review, a robust nylon part for repeated handling, or an early fit check before committing to a production-representative process. The right choice follows that evaluation goal.

Start with the question the prototype must answer

Write down the decision that follows the build. If the review focuses on appearance, fine geometry, ergonomics, or access, surface detail may lead the process choice. If engineers need to handle an assembly, exercise a snap fit, or evaluate complex interlocking geometry, durability may matter more. Lab Ready's plastic 3D printing capability uses SLA for high-detail resin models and SLS for functional nylon prototypes. Both can support fit evaluation, but the expected handling, geometry, and surface requirement determine which route is more useful.

Choose SLA for detail, appearance, and early mating checks

SLA is the stronger starting point when a smooth resin model and fine detail are central to the review. It supports visual design models, ergonomic studies, access studies, master patterns, and early mating checks. That makes SLA useful when a team needs to inspect form, confirm that a concept reaches the intended area, or discuss the design around a physical model. A resin prototype does not automatically represent final production behavior. Treat it as evidence for the questions it was built to answer, then identify any material, tolerance, or surface requirements that still need a later process.

Choose SLS for functional handling and complex nylon geometry

SLS produces durable nylon parts without conventional support structures. It is suited to snap fits, complex assemblies, functional handling, and prototypes that need more robust use than a visual resin model. This makes SLS useful when engineers need to assemble components, repeat a fit check, or evaluate unsupported geometry in a physical build. The choice still depends on the application: nylon can answer handling and geometry questions without claiming to reproduce final alloy behavior, a specified production resin, or a finished precision surface.

Plan the transition beyond the printed prototype

Plastic printing is often one step in a broader medical device prototyping workflow. Once the design must prove final material behavior, tight mating features, a specified finish, or production repeatability, the route may move to CNC machining, metal additive manufacturing, or molding. For a metal-process comparison, use the existing DMLS vs SLM guide. Keeping the learning goal explicit at each revision prevents an early plastic model from carrying requirements it was never intended to validate.

For the next quote, send the CAD or drawing and state whether the build must prove detail, appearance, fit, functional handling, or a later manufacturing decision. Use the prototype RFQ checklist to include quantity, material, finish, critical tolerances, inspection needs, mating-component requirements, and the target delivery date.