First, as I said, the "parts" here are dictated by their functions. One of the reasons that I posted this is that a lot of what is done with MOI is aesthetic -- that is, the object is to make something Look a certain way. My work has to be turned into machine parts that have to function, and not just look nice. That object that you did the rendering of is part of a piston, which will see 9,000-rpm in that cylinder. The problems then are quite different. One "part" has to do one thing and the next "part" has to do something else. But these "parts" have to come together into One Part. Without understanding what the engine does, how it operates, you can't appreciate Why every detail of this cylinder must be very nearly as it is. And when I put these "parts" together, I can't compromise their function in order to accommodate the limitations of the software I'm using. And the beauty of MOI is that I don't have to compromise. But there may be other ways of getting the job done. I haven't seen anyone else solving the sorts of problems that I have to solve, so I developed my own techniques. I would be very happy if someone could show me an easier, faster way to do this. But what I've found on the Forum are people getting stuck doing things that I think are trivial. I must point out that in this last example, when I look at the "parts" that I must bring together, there is no one solution to the problem. This is why I have to draw a bunch of lines and keep trying different ideas until I find something that works. And solving this problem doesn't help much when I get to the next configuration -- every arrangement is different and requires a unique solution. But my method always works.