What to put inside the pockets of a swimming costume

I only had a lumpectomy - however, my Mum had a single Mx and she uses a foam insert.  I think she got it through the breast care nurses.

Just found it....  company called Nicola Jane does them.  Look for featherweight form swim breast form.

If u have had a mastectomy then My breast care team provided a prosthesis and went for a fitting marks and Spencer’s do post surgery swim wear and the prosthesis fits inside the pocket the prosthesis is water proof too