You are confusing UI with mechanical design. It's like confusing learning Python with producing solid software products. OK, let me illustrate the point with

You are confusing UI with mechanical design. It's like confusing learning Python with producing solid software products. OK, let me illustrate the point with a question: You have two parts that attach to each other. The parts are joined using a set of six 5 mm bolts with washers and locking nuts. The hole pattern is circular and has a radius of 3 inches. What are the minimum diameter and dimensional tolerances you should specify in order to guarantee mating across multiple parts and across thermal variations? OK, same two pars. Now they mate using no screws. They use a one-time-only locking tab and catch system along the inner periphery. What's the geometry and what are the tolerances? Interestingly enough, none of the above talks about how to use the UI of some 3D program to solve the problems.