Thank you Julian, I appreciate your reply. I have been away for quite a while, and I have engaged in a project which will require both kinds of resources.
You see, I once used A-Libre which had components behave like solid pieces within the 3D environment. That is, components or groups did not merge into one another, but "bumped" and were stopped by the boundaries like they were physical boundaries. Gears and levers actually pushed and made other gears spin when engaged. That way a designed gearbox would always behave like actual gears making the end shaft spin at the proper calculated speed.
Of course we have the snap points in SU, but I need pieces and components and groups to show actual solid features, so I may not have them fit beyond specific tolerances.
Have a great day.