Ice Release Device

This is a standard timed release mechanism that uses ice and simple physics to attach rope to an anchor point.  There are many varieties in the design, but I have a few tips to make it safe and secure.

I typically use a small metal ring with a piece of string attached to it using a lark's head knot.  This is easy to undo, and cannot be removed once attached to the anchor point.

Next I place one ice cube in a small ziplock bag and squeaze all of the air out.   This prevents water from dripping everywhere, which prevents damage to hardwood floors and mold growth under carpets.  A little bit of moisture will still develop due to condensation, but that should evaporate without any harm.

I then roll up the ziplock bag into a tube and insert it into a sock.  I like using socks because I always have at least one that's missing a pair, and they're fairly strong.  And if I ruin one, it's no big deal.  If I'm using this method for suspension purposes I use an umbrella sleeve - they come on new umbrellas and are typically thrown away or lost, but they're the perfect design.

I finally slide the sock through the ring which is sized just right to prevent the ice from slipping through until enough melts away.  I usually tie a rope to the end of the sock using a lark's head which won't slip off the neck of the sock.  This gives me plenty of rope to secure me but keep me away from the device to prevent tampering. 

I typically use just one or two cubes because being wrapped in plastic without air slows the rate of melting significantly.  One cube will typically last me a half hour.  But the size of the ice cube, the diameter of the ring and the ambient temperature of the room can all vastly change the melting duration.  It's always best to experiment separately from any bondage scenario. 

I once tried to implement a story online where the protagonist used 12 ice cubes - I did half the number for the test and after 5 hours of playing around waiting for the device to release I realized how dangerous recreating the scene blindly could have been.