Use low-volume 3D printing while demand is uncertain
3D printing can help test a product, collect customer feedback, and fulfill early orders before tooling costs make sense.
Injection molding fits proven scale
Molding can become attractive when the design is stable, demand is proven, and the economics justify tooling and larger inventory.
The methods can be sequential
A product can start with 3D printing, improve through real customer use, then graduate to another process when the business case is clearer.