For the mask, I silver spray painted a plastic mask I got from a party store, then I brush painted a design on it using black acrylic paint, and went over it again with a silver acrylic paint pen (except for the grill of the mouth). Lastly I did a super light spray of black spray paint all around, and especially around the eyes to give it a darker look.
I bought Marvolo's ring a long time ago, so I thought it was fitting that I wore it with this costume, and I bought the lacey bracelet, because I thought it would be a nice cool detail to go with the look.
No death eater costume is complete without the Dark Mark and a wand. I bought the dark mark tattoo on Amazon Smile (benefitting the Oakland Interfaith Gospel Choir). The wand I made on my own a while ago using a wooden dowel, hot glue, and acrylic paint.
And finally, if you look at the photos of the Death Eaters, they don't really wear a cape, but it's more like a long hooded vest. So I bought a long black cape, also from Amazon Smile, and I cut open the seams where my arm would go through. I cut 10 inches of the seam, and it fit my arm just right. It's a stretchy fabric, so it didn't dig into my arm or anything, but I think next time, I'd give myself at least 12 inches.
My clothes underneath the cape were mostly things that I already had. From the inside out: leggings and a camisole, then I wore over the knee boots from Torrid, a corset from Adore Me*, and threw on a shrug so I had some sleeves going through the armholes of the cape.
*A note about the corset, I am a size 18/20 and I bought their 4XL corset and it was way too small. I ended up buying satin ribbon from Michaels and re-laced it so that I could wear it. It didn't really matter anyway, since the cape was gonna cover the back, and I was wearing a camisole underneath; it looked fine from the front.
So there it is... my easy peasy plus-sized female Death Eater DIY costume!!!