FlexScan3D is described as 'The powerful 3D scanning software empowers makers to build an affordable structured-light DIY 3D scanner based on the same engine that powers Polyga’s professional 3D scanners' and is an app in the Photos & Graphics category. There are five alternatives to FlexScan3D for Windows, Linux and Mac. The best alternative is ReconstructMe. It's not free, so if you're looking for a free alternative, you could try 3D Underworld or SLStudio. Other great apps like FlexScan3D are DAVID-Shapefusion (Freemium) and DAVID-laserscanner (Free).
Structured light scanner is a tool to reconstruct point cloud from series of images lit by patterned light. As showing in the following image, patterns are projected to the object in the grid manner. Each cell in the grid has a unique sequence.
DAVID is a software for 3D laser scanning. All you need to build a 3D scanner is a PC, a camera (e.g. a webcam), a background corner, and a laser which projects a line onto the object you want to scan.