Lack of heat energy in the surrounding area to warm it up.
Metalic cups keeps the water cold and it can be also used to keep the water hot .
Keep in the refrigerator or if u want it REALLY cold try freezing it
Ice..
The water would have to be colder than the ice to keep it cold. That is not possible unless it is brine(salt water). Then ice at 32f could be cooled by brine at say 30f.
put them in cold water
Warm air and warm water. Cold air and cold water keep ice cooler longer.
take the ripcrd and keep it in hot water for 2-3 minutes and then take it out it would be soft and keep it in cold water and straighten it with ur hands. first straighten it and then keep it in cold water
3 to 5 days.
you just keep it in clean cold fresh water.
keep cold and ends in water
like you keep a tropical water fish only you should provide it cold water instead warm water.
fur