Hi Mark, I'm not familiar with DesignCAD 3D Max - it looks like it may be related to TurboCAD and it seems like it may be a kind of cut down feature limited version of TurboCAD or something like that?

From what I could see on its page here:
http://imsidesign.com/Products/DesignCADSeries/DesignCAD3DMAXVersion21/KeyFeatures/tabid/1834/Default.aspx

it seems to be more focused on importing only 2D drawings from other programs, you would probably be better off with the full version of TurboCAD that has more functionality in it - you should be able to more easily take MoI models into the full version of TurboCAD while that 3D solids import functionality looks like it may be missing from DesignCAD 3D Max...

But I'm not really sure about it since I'm not familiar with it and I'm just going by the description on their web site.

- Michael