Dan, I do store a lot of wood, a lot more than necessary, but, each time i go to a lumber yard, Home Depot or Lowe's I'll look for anything I think would look good in a future Intarsia and pick it up. I have four 30" X 48" vertical storage cabinets along side the house where I store the boards. I try to keep them sorted, according to the various shades of color, in three of the cabinets and in the forth one I store all the hard woods. And, out behind the workshop I have six large Totes where all the small leftovers end up. I also store a few sheets of 1/4" Mahogany plywood against the wall in one corner of the garage to use for backings.
The unfortunate thing is, I never seem to have the exact board I need for a particular project. lol
