I actually made this costume several years ago as I needed something comfortable to wear to a convention I was asked to be a guest at, and because a friend at the time was making Saber. I've always been a fan of Type-Moon's Fate series, so Rin's default outfit was an easy choice. While I don't feel that I suit her very well (I'm a much better (Medusa) Rider, who is also my favorite character from Fate/Stay Night), it was still fun to cosplay her and have something easy to get into and wear around a busy convention!
This costume was super easy to make as it's basically just a turtleneck and pleated skirt. I spent the most time and money on the wig, which is a very high quality skin top; when I was wearing it, everyone thought it was my real hair!