I stumbled across an explicit 3D CAD package today - CoCreate from PTC.
The best part about it is that they are offering a free download with a lifetime licence to anybody willing to fill in a registration form.
Part of their blurb..,
CoCreate Modeling PE puts the extraordinary power of explicit modeling into the hands of any engineer, designer, or student. Even casual users and hobbyists can use it for their home projects, especially with the help of our Quickstart projects, online help, and user forums.
I've downloaded it and it seems quite useful. I've had less than a hour playing with it so I can't offer a better informed opinion.
Info and download from here
I've got absolutely no connection with PTC whatsoever but, if you want it, get it now because from past experience their free downloads do tend to dissapear after a bit.