Manual tugging
Manual methods of foreskin restoration consist in creating tension with the hands for periods of time. Typically one hand is used at the base of the penis and the other hand at a point of equilibrium after covering the glans. Some restorers may choose to perform exercises for a certain time daily, i.e. 20 minutes in the morning and 20 minutes in the evening, while others may choose to tug for one minute every time they go to the bathroom.
Similar methods can be used to overcome phimosis (by enlarging the opening of the foreskin) or frenulum breve by stretching the frenulum.
Manual exercises are explained here: