Yes, there is. It's a LOT of work, and I'm not sure why you'd want to do it, but here you go. I'm assuming that your modeled part represents the post-plated form. Ensure that you have the accuracy set fairly high. If the process fails, you probably need more accuracy. Don't feel like you have to adjust it up-front, just bear this in mind as you go forward. Set selection mode to "geometry." Pick all the surfaces which would be plated. Once all of the plated surfaces have been chosen, "EDIT -> COPY" and then "PASTE." You can play with the interface at that point (selecting within boundaries, or omitting "fill holes" and so forth) but once you complete the "paste" step you'll have a new surface quilt feature, totally coincident with the existing geometry surface. I usually "hide" that surface at this point, by the way. You can then "offset" the surface (not "thicken," mind you!) by the appropriate plating thickness. This is where accuracy becomes an issue, because if your accuracy isn't sufficient, you'll be limited to offsets greater than what you want. The end result is that you'll have created a "quilt" surface, inside of your real part, which represents your pre-plated part size. You can then dimension to the surfaces and edges of this, rather than to the "real" part dimensions. I'm not sure it's really worthwhile to do this, though... I almost always just specify "after plating" or "before plating" on the dimensions shown on my drawings.
