Closeup pic of this cues Build Log, the Excel spreadsheet. I cut and paste values from my Wood Log into the Cue Log when I select my materials. All my wood is stamped with an ID, measured, weighed and logged. When I build a cue, I select the pieces I want and put them in the Cue Log, I then figure out, based on their weights, if I need to core, with what material, and so on.
Like I said, it's still being proven out, I need to document some more materials and such, but so far it gets me within .2 ounces before I even start building a cue.