I felt like this was going to be a short post if I only did one of these pieces, so I smooshed em together. These are hopefully really straight forward and help you for future builds as well!
BOOTS: For the boots, I found a pair on Amazon for about $20, and once they arrived (thank you Prime), I cut the tops off and held em together with duct tape. I may go back over them again once I have time to with bias tape so that it looks more finished, but we'll see. I cut out six strips of 2mm foam to make it look like the belts and then made foam "buckles" as well. Make sure you measure around your boots to ensure your strips are going to be long enough. I then took e6000 to the straps and held them there with tape. While those were drying, I cut out 6 rectangles from the same foam and glued them on with the e6000. I had to tape them down with masking tape to make sure it didn't lift up while I was doing something else.
Once those were dry, I added on the "buckles" and painted the straps the weird grey (in some reference photos, it's black, in some it's grey) then I splatter painted the bright green onto the boots and we're done!
NECKLACE: This was also super simple and straight forward. I took a small chunk of sculpy and molded the piece into her skull, making the eyes indent with my thumbs, and drawing the lines on it with a knife. Then I put it in for too long and burned it, but that's okay because I needed to paint it grey anyway. Make sure you make a handle so that you can loop thread or anything else to the necklace. I sewed it into the necklace, and used a scrap of performance fabric folded over and flipped. Sew tiny pieces of velcro or hook and eyes onto it, and you're finished with that piece too!
GLOVES: These are pretty straight forward as well, but please remember that Jinx has one of each color of the gloves. Her right hand has the purple, while her left has the black. You'll make a template using your hands on paper, then cut it out. Place and pin it on your fabrics (best to use stretchy fabric/performance fabric) and cut that out. Sew carefully and slowly around the sides. Remember that her gloves are fingerless, so you don't need to sew fingers. I added in an extra strap at the bottom because I have tiny wrists compared to my hands, so I made a strap a few inches longer than my gloves, and attached velcro to the ends and where I felt it would be most secure on my wrists.
For the black glove, she does have a piece of "armor" on it, which I cut out of 2mm foam into the weird B shape and painted it with silver, then sealed it with mod podge. My dumb self forgot that her left hand had the armor, so while the piece was still drying, I tore it off and glued it to the right side. There were glue marks, so I kinda covered them in the "zombie green" paint I used for everything else.
Thank you so much for checking out my build for Slayer Jinx's boots, necklace, and gloves! If you have any questions, comments, or concerns, please let me know, I am more than happy to help you get easier clarification!