I’m hooked on hooks hooking. Cloth covered hooks are a great way to add or modify a costume to be removable (or more easily removable). They are metal hook and eyes, with a layer of fabric covering. I replace all of my bra attachments with these and use them on other things like skirts, wraps, etc. You can find these online or in craft stores. My local store keeps them stocked in black and white, and sometimes brown. I try to keep a few on hand because I will often be working on costumes at odd nightly hours when only bats and vampires should be productive and most stores aren’t open. You can dye, or even easier – color the white ones with permanent markers, to make them match your garment. I imagine you could use paints also, but that would likely chip away. 

When I’m using these for the back of a bra, I will remove all of the standard hook closures and then sew the hook directly onto the ends.  Because my bras tend to have 3-5 rows of hooks due to carrying around boulder boobers, I will sometimes change the shape of the ends to be more of a trapezoid instead of a rectangle, then it will look better if I’m only using one cloth hook. If the ends don’t overlap and I leave them as huge rectangles, having one hook with leave a space between that makes me feel have weird feelings.  There are times where I will use fabric to make completely new ends. This usually happens for me if I need to extend the circumference of the bra, if I’m building a bra from scratch, or if I’m Frankensteining things together.