ETA, October 13, 2014: Annele from Make Bra informed me that the shipping cost for 5 pieces of foam (roughly one yard) to the United States is 20€, making the shipping cost per piece 4€ (about $5). Meanwhile and the shipping cost for 22 pieces of foam (just over 4.75 yards) is 35€, making the shipping cost per piece only 1.59€ ($1.25). So if you are planning on making more than a couple of bras and like the foam, stock up! If you plan on ordering more than 22 pieces contact Annele so she can figure out the best way of shipping it for you.
ETA, October 8, 2014: I tried the Make Bra foam and it is by far the nicest foam and easiest to work with. It really is worth the additional cost.
Someone commented on one of my Make Bra reviews (DL01) on PR asking where I got the foam to make the cups. That particular bra was made out of Pre-finished Foam Padding from Bramaker’s Supply. You can find it on their website by going to Fabrics > Linings & Paddings > Pre-finished Foam Padding. It is $30/meter for a 30″ width. I bought it in August 2011 for $15/meter, so since then it has doubled in price! If you buy just one meter it ends up costing $50 with shipping. The benefits to it though are that it comes in white, beige, and black, and the texture is very soft and slippery.
Sew Sassy sells the foam padding as Poly Laminate Foam. The benefits are that it is almost half the price of BMS ($17 for a 60″ width) and the shipping is a lot more reasonable. The downsides are that it only comes in a yellowish beige color, so if you want to cover it with lace it won’t have the prettiest background. The texture is a softer, more matte fabric that isn’t as luxurious as the Bramaker’s foam padding but the much lower price makes up the difference, especially if you’re doing a lot of bra “muslins” and don’t want to commit to a $50 piece of foam yet.
Fabric Depot has padding listed as Tricot Bonded Poly Filler. I have not sampled this fabric, but it comes in 50″ widths in both white and nude. There’s volume discounting available, but I doubt most people are going to buy 10+ yards of this!
Make Bra sells the foam in cut pieces suitable for one bra in black and white.
Elingeria also sells it by the pieces, but also by the meter. The by-the-meter price is actually slightly less expensive than the American sources at about $16.25/m for a 51-55″ width and comes in black, nude, and white. The by-the-piece foam comes in white and nude and the dimensions are 9.75″ x 13.75″. Unfortunately Elingeria appears to be out of stock of all of the foam, so I couldn’t order any to judge the quality.
In addition to the sources above you can also find it sporadically from Etsy sellers.
I much prefer the made-by-me foam cups to the molded ones because the foam is softer and the fit tends to be a little bit better. You can tweak the pieces so it hugs the neckline a little better if you are shallower on top or remove some of the width from the sides if you have a narrower frame. With molded cups you either fit into them or you don’t and lots of issues like gaping underarms or necklines happen. I have not done it myself, but Annele from Make Bra says that bras made from this type of foam can be washed in the washing machine. Anytime I’ve done that with the molded foam bras they ended up rippled and wrinkled and they don’t smooth out during wear. To sew the foam pieces together I use a 3-step zig-zag stitch and butt the edges right up to each other. I then give it a gentle tug and if there’s any places where there’s a slight gap between the edges, I resew over that section only. The key is to push the foam edges together very firmly while stitching.
While I will definitely still make unlined/lightly lined bras I think a lot more of what I make will be these foam cup bras.