Musical composer's pen

I chanced across this 5-line staff liner on Amazon—a pen with five ballpoint tips in a row, for musicians to quickly write musical notation—and impulse bought it. I can't read or write music, but it'll make a great gift for someone else who can't read or write music.

These pens are formally known as rastra, and old ones are bizarre and beautiful. Stylophiles sometimes lament the astronomical prices they fetch at auction. An Etsy seller from Ukraine will make you a handsome handmade ballpoint rastrum for a more reasonable price.

Rastrology [is] the study of the use of the rastrum, is a branch of music manuscript studies that uses information about the rastrum to help find the date and provenance of musical materials.

Someone on eBay sells five-pointed nibs for a few dollars, if you insist on dipping the ink and don't have a grand to blow on vintage finery.

See also the Stravigor, a more precise (but less versatile) gadget that uses a roller instead, invented by Igor Stravinsky himself. Here's a modern derivative in action:

A ruler available in Japan called the Lineslider offers another method.

And theres always the musical typewriter: