Sometimes I find that I've accidentally deleted a curve or surface, or I might just want to step back to an earlier version of an object, but I don't want to lose progress I've made elsewhere in the file. In this case I open an earlier version of the file in a separate instance of Rhino.
1. Start another instance of Rhino. Open the earlier version of the file.
2. In the earlier version, select the object in question and choose EDIT > COPY (not TRANSFORM > COPY) .
3. Switch to the newer version and choose EDIT > PASTE. The object is pasted into a layer corresponding to the one if was copied from (i.e. it will create one if that layer didn't exist in the new file) and at the proper coordinates.
