* A spare shuttle (I like the kind that double as beaters) for tablet weaving. My current one is attached to a half-finished project that I really should complete sometime. :-)
* Period-style snips for cutting thread. (on back order!)
* Period-style shears for cutting fabric. (I'm not sure whether Historic Enterprises' 4-inch-long spring shears are adequate for that purpose, but they would at least fit into my box).
* A needlecase.
* Possibly, a ring thimble. Turns out Historic Enterprises makes a 14th century design that's probably little different from any available in the Viking Age for only $5.95 USD. (This item remains only a "possibly" because I'm still not convinced that Viking women used thimbles, let alone metal ring-type thimbles.)
While I was looking for period-style shears, I found this site by SCA member Coblaith Muimnech, describing how she assembled a medieval sewing kit for a gift exchange. Interestingly, the thread holders she documented and made are similar in form to the ones I just bought on EBay. That was very satisfying.