The last surgery that is undergone in female to male (FTM) reassignment treatment journey, and which is undergone by very few FTM transsexuals, is bottom surgery.
As with the case of top surgery, there are different techniques. Many FTMs don't opt for bottom surgery, as the surgical techniques are not very advanced, and there is more to being a man than the presence or absence of a penis.
Genital reconstruction is a lot more expensive and has far greater risks than top surgery.
Genital reconstruction falls into two basic types: phalloplasty and metoidioplasty.
The more contemporary phalloplasty technique is called the free tissue flap transfer (FTFT). This technique has been made possible by the advent of microsurgery, and the development of the fine art of connecting dissimilar nerves. A flap of skin and muscle tissue from the forearm, groin, or thigh, is transferred with its existing nerves and blood vessels to the groin area, and then microsurgically connecting the nerves and blood vessels to the nerves and blood vessels of the groin.
This results in a penis that may have feeling, but is not capable of achieving or sustaining an erection. Although implants are available to achieve erection, they have so far proven to be problematic due to infections, rejection by the body, and extrusion and intrusion.
The metoidioplasty technique is the other available technique for creating a penis-like structure on an FTM. This technique uses the clitoris, and transforms it into a more male-looking structure, providing there has been sufficient clitoral growth induced by testosterone. The process involves the release of the clitoris, which basically means that the ligaments that hold the clitoris in a position are severed. The result is a micro-penis. The scrotum is formed by joining the labia majora and using silicone testicular implants, sometimes preceded by tissue expanders.
This procedure allows the FTM to have a penis that is normal in appearance, with a natural glans and foreskin, as well as the appropriately sized scrotum. Sexual function is retained, and the FTM can have natural erections and orgasms. - (Health24)