I’ve just bought myself a little roll of stick-on, peel-off manuscript tape;
(image from amazon, but I bought mine from www.musicroom.com for £5.99 – a bit cheaper than amazon)
It was one of those sorts of things you add to an order to get the free postage, but then turns out to be surprisingly useful.
I am a dab hand at drawing freehand straight-ish lines to create manuscript paper in the margins of sheet music, or in practice notebooks, so the tape wasn’t a totally necessary item. But the idea of using it to simplify a bar (say, when the ornaments need writing out, or a chord needs re-arranging because of the stretches) struck me as being Really Useful.
It is also worth it for the “bling” factor – young pupils are dead impressed when I tear off a few inches and stick it into their book.