Minerva's outfit is a purchased pattern written for Mattel's Kelly doll (Barbie's very little sister), from Helga Kraft. I tweaked it ever so slightly to fit a slightly taller and slightly pudgier doll. However, I can share with you Minerva's Halloween mask, which should fit similarly sized dolls like small BJD's, Riley, and others.
Minerva's Halloween Mask
Have a frightfully fun Halloween!