"The exception is that MoI does have some limited amount of history in it, if you generate an extrusion from a curve in MoI it is then possible to edit the curve and the extrusion that was created from it will update but not if you have done other operations on the extrusion like additional booleans after the extrusion was finished."

This is exactly what I want to do! How do I do this, please? :-) I've noticed that when you create a solid via extrusion, the curve you use is left behind. I normally delete this because it gets in the way of easy selection of the solid. Are you saying that if you edit THIS curve, the solid will automatically re-extrude?

I'm familiar with the parametric-type CAD programs you're describing. I've used VectorWorks for many years. I find myself liking the MOI way, where the solid is just the solid as you operate on it and it has no notion of where it's from, sometimes. Sometimes I miss the ability to go back and edit the two cylinders (for example) that the soild is made from. On the whole, I VASTLY prefer MOI, so I'm sticking with it for now. Thanks!

Christopher