How small can a sutra be?

“The sutrah that the person praying places in front of him — it is best that it be about the height of the back of a saddle, approximately two-thirds of a cubit. If it is less than that, there is no problem; even something like an arrow or a stick is sufficient.” — Majmūʿ Fatāwā Ibn ʿUthaymīn (13/326)