Two file types come up constantly when quoting a job. They are not interchangeable, and sending the right one gets you a faster, more accurate estimate.
STL — a mesh of triangles
STL describes only the surface as triangles. It is perfect for 3D printing, but it carries no features, units are ambiguous, and it cannot be edited parametrically.
STEP — a real CAD model
STEP carries exact geometry, units and features. It is what you want for machining, mesh-to-CAD work and anything that needs editing or precise tolerances.
A rule of thumb
Printing something as-is? STL is fine. Need it modified, machined or reverse-engineered? Send STEP if you have it — and if you only have a mesh, that is exactly the job we do. You can also upload either to our instant estimator.