Jerry - what do you fuse the borax in? And then how do your get it out??
I would not allow the borax to cool in the crucible but rather pour it out immediately after the fusion. I would use the unglazed side of a tile. The solid will have to be ground up in a mortar. However as I said before it's easier just to buy the stuff. Years ago on a weekend when everything was closed I had to make some anhydrous sodium metaborate by fusing borax and sodium hydroxide.
A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.