An idea from the Internet:

The slave earns the right to a 5-minute release once a month if all tasks are completed to a satisfactory condition. Release constitutes the belt being removed and the slave allowed to masturbate itself for the period of 300 seconds – the slave is permitted to cum as many times within this period. If the slave fails to orgasm in this period then it shall wait at least one more month for another release opportunity.

The following tasks must be completed in any one month (a month constitutes 4 calendar weeks):

• ten litres of piss are to be consumed via hood.
• fifty six hours of locking plug use spread as required over the month, 2 periods of 6 hours minimum wear must be achieved
• one night spent in cage from 8pm – 8am
• 4 sessions of electro plug training minimum 1 hour each.
• 24 strokes of cane
• 5 consecutive days of 24/7 nappy wear
• 8 days of forced attire at least one while nappied

Many different chastity devices are available from Mr S