We were no longer able to get our previous cut and sew foam once COVID hit, so we sourced a different one. The new foam is more stable rather than being more drapey and stretchy, so it will work as a base layer for medium to large cups in addition to the smaller sizes.
The best way to get a foam cup to fit you is to make your own cup out of a stable foam like this, using your well-fitting bra pattern. Cut off the seam allowances within the cup and zigzag the butted seams. For the largest cups, use an additional layer of Sheer Cup Lining for support, or cover with a stable fabric. For a great T-Shirt bra, use this me-made cup and cover with a knit like our Microlycra or yummy bamboo jersey.
Our new cut and sew foam is a perfect addition to your bra building stash. It is about 1/4" thick and is available in nude. It is 25" wide, and is sold by the half yard.