Brian,
Not sure if this is too old of a post to submit this too, but I'll try anyway. Shelling and thickening can many times be the biggest headache in complex modeling, Creo has added some tools to work with this issue, but much more is desired. I'd like to see a usable "approximate offset" feature. CATIA has this feature, but the results can be very unexpected (usually not acceptable).
Many parts only really need one machinable side (i.e. thermoformed, blow-molded, rotational molded). Other times, one only needs a quick part for concept exploration. Many times, a part needs a little extra thickness for an SLA build. Thermoformed parts may only need the shell feature to show on a part drawing, but the shell side will never be machined. Why then, would we need to spend so much time building a two-side machine-able model.
It is usually very small (insignificant) surfaces that make a shell/thicken feature fail. GeoMagic (I believe to be a polygon modeler) has never had a problem thickening our ProE models to any thickness we desire. It seems that Creo's sub-division surface (Freestyle) surfaces also do not have a shelling/thickening issue. Given these observations, I propose one, or both of the following:
1) A shell/thicken option that would create a approximate offset, with the system determining how to patch small surface that typically might fail. Possibly add some user input such as: Ignore surfaces smaller than ___. This shell/thicken feature would still be machinable both sides.
or
2) A shell/thicken feature that basically creates a polygon mesh on the shell side. This would be helpful when a machinable shell is not required (i.e. thermoformed, blow-molded, rotational molded parts). You could still create part drawings, place in assemblies, export to SLA, etc.
If this capability was added, I believe Creo would have a huge advantage over other CAD systems. I know it would be a big hit in the packaging industry.
-Mark