This is a free pattern called "Brenda's Shrug". I've made several for myself and others, and have found it to be an easy to read and easy to execute pattern. I've never made a 3/4-sleeve version, but think it would be possible to alter it for that, and for size as well. The pattern is worked flat, with the sleeves seamed. If you have experience working sleeves in the round, you may work the sleeves that way to avoid seaming.