A swim-friendly breast prosthesis needs to be lightweight, water-resistant, and quick-drying, which makes it a different project from an everyday breast form. The good news is that you can make one at home with basic sewing skills and inexpensive materials. The key is choosing fillers that don’t absorb water and fabrics that dry fast, so the form keeps its shape and weight in the pool.
Why Regular Prostheses Don’t Work in Water
Standard silicone breast prostheses are heavy on land and even heavier when wet. Foam-filled forms soak up water like a sponge, becoming waterlogged and misshapen within minutes. Neither type dries quickly, and trapped moisture against post-surgical skin creates conditions for irritation or infection. A swim prosthesis solves these problems by using materials that repel water entirely.
Materials You’ll Need
The filling is the most important decision. Polypropylene pellets (sometimes called poly beads or stuffing beads) are the most popular choice for swim prostheses. They’re the same plastic used in medical-grade equipment and FDA-approved food containers, resistant to both bacteria and chemicals like chlorine. They don’t absorb water at all, so they drain and dry within minutes after you leave the pool.
For the outer shell, choose a swimsuit-weight lycra or nylon/spandex blend. This fabric stretches to create a natural shape, dries quickly, and feels comfortable against skin. Avoid cotton or flannel, which hold moisture. You’ll also need:
- A sewing machine (or a needle for hand-sewing with very small, tight stitches)
- Polyester thread, which won’t weaken in chlorinated water
- A measuring tape and scissors
- An existing bra cup or breast form to use as a pattern template
- Polypropylene pellets, available at craft stores or online (about one to two cups per form, depending on your size)
Creating the Pattern
The simplest approach is a teardrop shape, which mimics natural breast contour when placed inside a swimsuit pocket or mastectomy swim top. Take your existing prosthesis or a well-fitting bra cup and trace around it on paper, adding half an inch on all sides for seam allowance. If you don’t have a form to trace, fold a piece of paper in half and draw half a teardrop shape along the fold. The widest point should sit roughly at the center, with a gentle taper toward the top and a rounder curve at the bottom.
Cut two identical pieces from your swim fabric using this pattern. For a more three-dimensional shape, you can cut a third piece as a side gusset, a narrow strip about one to two inches wide that runs along the curved edge between the front and back panels. This gusset adds depth and projection, making the form look more natural under a swimsuit. Without it, the prosthesis will be flatter, which works fine for smaller cup sizes but may look too pancake-like for larger ones.
Sewing and Filling the Form
Pin the two fabric pieces together with the “right” (outer) sides facing each other. Sew around the edge using a narrow zigzag stitch, which allows the seam to stretch without popping. Leave a gap of about two inches along the top edge for filling. If you’re adding a gusset, sew it between the front and back pieces along the curved lower edge first, then close the remaining seams.
Turn the pouch right-side out through the gap. Now pour in polypropylene pellets a little at a time, cupping the form in your hand to check the shape and weight against your other breast. You want enough pellets to fill the space without packing it tight. The form should feel soft and slightly shifting, not rigid. Once you’re satisfied with the volume, pin the opening closed and try it inside your swimsuit to check the look before committing.
When you’re happy with the fit, fold the raw edges of the opening inward and sew it shut with a tight zigzag stitch or a hand-sewn whip stitch. Double-stitch this closure since it’s the most likely point of failure. Run a second line of stitching around the entire perimeter if you want extra security against pellets escaping through the seams.
Adjusting Weight and Shape
Polypropylene pellets are very light, which is an advantage in water but can make the form feel too buoyant. If your prosthesis floats up inside your swimsuit, you can mix in a small amount of glass beads or aquarium gravel to add weight. Start with a tablespoon at a time and test in the bathtub before heading to the pool. The goal is neutral buoyancy, where the form neither floats to the surface nor drags downward.
For a smoother outer contour, some people add a thin layer of polyester batting between the pellets and the outer fabric. Cut a piece of batting to the same shape as your pattern, lay it inside the pouch against the front panel, then pour pellets behind it. This prevents the beaded texture from showing through thin swimsuit fabric. Use polyester batting only, not cotton, so it dries quickly.
Wearing It in the Water
The most secure way to wear a DIY swim prosthesis is inside a mastectomy swimsuit or bikini top with built-in pockets. These pockets hold the form snugly against your chest wall and prevent shifting during movement. If you don’t have a mastectomy swimsuit, you can sew a simple pocket into a regular swimsuit by tacking a piece of swim fabric to the inside of the cup on three sides, leaving the top open for inserting and removing the form.
After swimming, remove the prosthesis from the suit and rinse it under fresh water to flush out chlorine or salt. Stand it upright or hang it in a mesh bag so pellets drain completely. It should be dry within 30 minutes to an hour, far faster than any foam or fiberfill alternative. Rinse after every swim to keep the fabric from breaking down over time.
Protecting Sensitive Skin
If you have scarring, radiation-treated skin, or any area that’s still healing, direct contact with pool chemicals can cause stinging or irritation regardless of what prosthesis you use. Lining the back panel of your form (the side against your body) with a soft, moisture-wicking fabric like microfiber creates a gentler surface. Some swimmers also apply a thin layer of barrier cream to the chest wall before getting in the water, which reduces chemical contact without affecting the prosthesis.
Check your skin after the first few swims for any redness or irritation, particularly along seam lines where the form presses against you. If a seam is rubbing, you can cover it with a strip of soft iron-on seam tape or simply flip the form inside out and re-sew it with the seam allowance facing outward, then tuck that rougher side away from your body.
Making It Last
A well-made polypropylene-filled swim form typically lasts one to two full swimming seasons with regular use. The fabric wears out before the filling does, so inspect the seams monthly for thinning or small holes. Chlorine degrades lycra over time, which is why rinsing in fresh water after each use matters. If you notice pellets starting to poke through the weave, it’s time to transfer the filling into a new shell rather than risk losing beads in the pool.
Having two forms and rotating them extends the life of both, since each gets time to dry completely between uses. Store them flat or in a breathable bag rather than crammed into a swim bag where compression can distort the shape over time.