Converting Altium STP/STL model into solidwork
You can import the 3D STP model of the PCB into Solidworks but I don't think the features will be editable. Just RTFM and it should work, but as I recall it was a bit quirky (maybe some holes were not quite open, that sort of thing). 

There's supposed to be a new capability that allows editable features to be imported, according to some Solidworks sales guys that gave us a presentation (on another related product) last week. Not sure if it's extra cost or standard in the latest versions.