Gini - After you have you mastectomy and you're ready for reconstruction, your plastic surgeon will place an expander beneath your muscle that is filled with a little bit of saline. The outside of the expander is a very thick plastic like material, such as an implant. The main difference is that there is a valave located on it where each week once you are ready, you're doctor will use this magnetic device to locate the position of a tiny piece of metal where the valve is. then he will insert a long needle into your muscle and valve and add saline until you feel tight. The uncomfortableness will last a few days, yet you should get weekly fills. Depending on what size you want, it should take no more than 3 months from start to finish to swap it out for an implant. then about 3 months down the road you should be able to discuss having a nipple made.
It goes very fast, and it's not too bad. Just take a tylenol or something before your fills and the pain should be fine.
Good luck!
Angi