openSCAD uses a language somewhat reminiscent of C for creating models. A preview of the model is rendered alongside your code. Fully cross-platform, it runs on Linux, OS X, and Windows. Much like SketchUp, openSCAD can also extrude 2D outlines into models. This feature comes in very useful if one already has a set of technical drawings for a part. With no price tag, it’s pretty affordable during this costly season.