Two paradigms I previous sold SpaceCalim and have used it for a couple of projects. It is a good program but I never warmed up to it. There two paradigms for CAD design. The parametric history/feature based modeling and the Direct editing or Explicit modeling. When SpaceClaim came out there were a couple of direct editing only packages available KeyCreator and CoCreate. At the time of SpaceClaims release the history based systems were unable to edit non-native parts, SpaceClaim was designed to fill that gap. The wonderful thing is that now PTC Creo has CoCreate, Siemens NX and SE has ST, Autodesk has Fusion all are direct editing modules. I have experienced them all. All are very good and solve the problem of not being able to edit non-native parts. The problem is that they are only a bit better than having a stand alone package like SpaceClaim since the interoperability between the two systems is a bit clunky. So since that need has been filled, SpaceClaim now has to basically stand on its own as an explicit modeler. I feel we really need both paradigms to have a complete design solution. IRONCAD is the only product on the market that has both of these paradigm integrated into one system. I have been selling and using IRONCAD for years. I like the ability to have direct editing when working with a very complex part. I can bypass the history and work directly with the features. But when starting a project I want to use the parametric history/feature based design. I like IRONCAD, because like SpaceClaim it is a UDE (Unified Design Evironment) which means you can design your complete assembly in one file. This is very productive when doing conceptual design. I do a lot of work modifying parts and assemblies from SW, Creo, Inventor etc. and I can bring the native files in and work with them as if they were designed in IRONCAD. IRONCAD has an incredible set of native translators available. Also IRONCAD has a modeling only package, INOVATE, that is a great add-on for any system.