This project demonstrates a way to "loft" from one shape to another in OpenSCAD using the concept of tweening. Using this project, one can easily shift from a circle to a circle(of different size), a triangle, square, pentagon, hexagon, heptagon, octagon, nonagon, decagon, hendecagon, dodecagon, rectangle, trapezoid, heart, star, or cross. You can even add your own shapes or customize the default shapes for your own applications. Sample cases: you need an adapter to go from one hose size to another, you need to go from a rectangular duct to a trapezoidal duct, you need to drive a pentagonal bolt but only have a square driver, you need a hopper or a stand..... Due to limitations in OpenSCAD (variables, array concatenation, etc.) this project uses a python script to generate the tweens. This file "tween_generator.py" is where the shapes, and their resolution, are defined (and where one can customize/add new shapes). When run, it creates the file "tween_shapes.scad" (a default version of this file is included in the project). "Tweening" allows shifting from one shape to another by using a weighted average. For example, if tweening between a circle and a triangle - at 0%, the shape is a circle, at 100%, a triangle, and for all other values some amalgum of the two. The main project file is "tween_loft.scad". In this file, I document the program, the logic, and the parameters. There are several examples that use these two files to create a solid or a tube. You can either create solid shapes (stamps, press tools, etc.), or hollow tubes. All the parameters are controllabled - the size, rotation, and centroid position of your base shapes, the granularity of the loft, the thickness of the walls, etc. You can also create an extension of each base shape, which you could use as a mounting point for tube clamps or other hardware. The complexity of the design is controlled in two places. The resolution of the tween shapes is determined in the "tween_generator.py" file. The number of slices in the loft ("tween_loft.scad") also affects the complexity. If either value is too high, the computation time increases sharply. Values that are too high will also crash OpenSCAD. The program may work fine with a smaller number of horizontal slices, but may crash with higher numbers. Save your work often.