Handheld Scanners Create STL Files 

Handheld scanners can scan tubes and create STL files. The camera shown on the right is the Artec Eva. There are scores of cameras on the market.

An STL file is a commonly used file format for 3D printing and computer-aided design (CAD). It represents a surface as a series of small triangles, known as facets, where each facet is described by a perpendicular direction and three points representing the vertices of the triangle. The format approximates the surfaces of a solid model with triangles, and it is the defacto standard data transmission format for the Rapid Prototyping industry.

This is an example of a surface data inside an STL file.

Source site: https://markforged.com/resources/blog/how-to-create-high-quality-stl-files-for-3d-prints

Users can scan tube shapes, export the data to an STL file, and then import the STL file into VTube-LASER for measurement.