In this paper, a novel method is proposed for the prototyping of digitized data by means of rapid prototyping technologies without constructing a CAD model. Firstly, an optimized STL file (the de facto file format for rapid prototyping machines) is constructed directly from digitized part data. In order to reduce storage space and increase computational efficiency for subsequent processes such as slicing, significant data reduction can be achieved at users’ discretion by deleting data points in planar and near planar regions. Points around the ‘blank region’ left by deleted triangles are linked through re-triangulation to form triangular facets obeying STL file rules. To obtain optimized re-triangulation result, a genetic algorithm (GA) is developed and implemented. Finally, experiments on different amount of data reduction over a digitized sample are conducted with satisfactory results.