Have a nice mod that you aren’t really using anymore, but would like to use on your alt?
Extract the armoring/mod and place it in any sort of armor that is bound to legacy. You can then mail that legacy piece to another one of your toons and extract the piece.
It’s expensive (since you’re extracting the same piece twice), but if you have the money you can gear your alts up to par that much quicker. Really handy for those spare rakata trade-in’s you might have sitting in your bank, or the pre-set black hole pieces that drop from the pilgrim or Denova.