There are many halakhoth that say you can't eat meat and dairy, nor prepare it, nor sell it/derive benefit from it. Does the same apply to Shaatnez? As a more specific example, if one does not personally wear it, can one buy a Shaatnez garment for another to wear at a special event?
Shulchan Arukh YD 304 in its entirety says:
כלאי בגדים מותר לעשותם ולקיימם, ואינם אסורים אלא בלבישה.
Mixtures of clothing [ie Shaatnez] one may make them and keep them, and they are only forbidden to be worn.
So benefit is permitted. That said, 303:2 says:
אסור להלביש את חבירו כלאים.
It is forbidden to dress his friend with [Shaatnez].
So don't go giving it to other Jews to wear.