The Ice-Cup Body Cooler

Signature tool

Thermal relief instrument

—

Set the air temperature where you are. See the estimated cooling and how long one fill of ice lasts.

Air temperature — 36°C

Ice amount

What you're doing

Cooling power

0W

One fill lasts

0min

Heat load eased

0%

Sweat saved

0mL/h

Estimates from a simple heat-balance model — real results depend on cup size, skin contact, and clothing. This is comfort cooling, not a medical device.

The engineering

Why it works

01

Cold sensors, fast reflex

Skin is full of cold receptors. Chill a wide patch and the brain eases its "sweat now" command within 2–3 minutes. This is why the sweating stops so quickly — faster than your core could ever cool.

02

Blood near the surface

A large volume of blood flows just under the skin of the inner thigh. Cooling it and the tissue around it pulls real heat out of your body — tens of watts, steadily.

03

Nothing wasted to the air

Insulation wrapped around the cup aims all the cold at your skin instead of the hot air. One bag of ice keeps working for an hour or more.

Parts

What you need

A plastic cup with a lid, about 11–13 cm across and 18–20 cm tall
Foam air-conditioner pipe insulation (or any closed-cell foam)
Waterproof tape or glue
A knife or scissors
Ice — any kind
Optional: a small towel under the cup — ice sweats condensation, and this catches the drips

Assembly

Build it

Wrap the foam insulation around the whole outside of the cup and cover the bottom.
Leave two bare windows on opposite sides, about 5×8 cm each — these will touch your inner thighs.
Tape or glue the foam so it stays put and stays dry.
Fit the lid so ice can't spill when the cup tips.
Check the fit: the cup should sit between your knees with the windows against your inner thighs.

In the field

Use it

Fill the cup with ice and close the lid.
Sit, and place the cup between your thighs with the windows against the skin above your knees.
Wait 2–3 minutes. The sweating should ease.
Refill with ice when it melts — and keep drinking water.

Read this

Stay safe

This buys you time in the heat. It does not treat heat stroke — you still need shade, rest, and water.

This eases discomfort. It is not a treatment for heat stroke.
Sip water every 15 minutes, whether or not you feel thirsty — even after the sweating eases.
Never hold bare ice directly on skin for long — always keep the foam or cup wall between the ice and you.
Get medical help fast for confusion, fainting, a racing heart, or hot dry skin that has stopped sweating — these are signs of heat stroke.

Extra care

If it's for an older person

Limit skin contact to 15–20 minutes at a time. Then take the cup away and check the skin underneath before continuing.
If they have diabetes, nerve damage, or poor circulation, they may not feel that the skin is too cold — someone else should check it for them.
This device doesn't replace supervision. During a heat wave, someone should check in on an older person living alone.