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The "Boer Maak a Plan" Air Conditioner

Featured Project

A survival mechanism built from a polystyrene box and an old usb fan

Completed March 11, 2026

Technologies Used:

Polystyrene BoxOld USB FanFrozen 2L Coke BottlesThermodynamicsSiliconeSurvival Instincts
The "Boer Maak a Plan" Air Conditioner screenshot 1

The "Boer Maak a Plan" Air Conditioner

The Problem: Unbearable Desk Heat

Cape Town is HOT! Today the highest official temperature recorded was 42.1°C. It's a struggle: your're just trying to exist, but the ambient temperature is slowly melting your brain. Air conditioning is expensive, and confusing, and a standard desk fan just pushes hot air around like a convection oven.

I needed a solution that was:

  1. Cheap (ideally free)
  2. Immediate
  3. Capable of cooling me, not necessarily the whole room

The Solution: Thermodynamics and Trash

I looked around the garage (and Mambos) and found the holy trinity of DIY cooling:

  • A polystyrene cooler box (Mambos)
  • An old, dusty USB fan
  • Drain pipe bend lying around
  • Empty 2-litre Coke bottles

The Build

The engineering was... precise-ish.

The
The "blueprint" for the build.
  1. The Intake: I cut a hole in the lid of the polystyrene box the size of the USB fan.
  2. The Exhaust: I cut a "vent" and siliconed the drain pipe bend to it.
  3. The Engine: I filled the Coke bottles with water and froze them solid.
The components ready for assembly.
The components ready for assembly.
  1. Assembly: I placed the frozen bottles inside the box, put the lid on, faced the fan downwards into the hole, and plugged it in.

How It Works

It's simple physics. The fan forces warm room air into the box. The air circulates around the frozen thermal mass (the Coke bottles), rapidly cooling down. The now-chilled air is forced out of the drain pipe in my direction, creating a delightful breeze that is much cooler than the ambient air directly onto my face.

Performance Metrics

  • Cooling Time: ~2-4 hours per set of bottles
  • Noise Level: Mild USB whine
  • Condensation Risk: High (towels required)
  • Dignity Level: Critical Low

Lessons Learned

  1. Airflow matters: The "in" hole must be the same size and the "out" hole or back-pressure kills the fan speed.
  2. Ice maintenance: You need a rotation system. One set of bottles in the box, one set in the freezer.
  3. Polystyrene is messy: Cutting that hole created "snow" that I am still finding in the carpet weeks later.

Verdict

Is it pretty? No. Does it look like something from a post-apocalyptic bunker? Yes. But when it's 40°C+ and my brain is melting, this ugly white box is the most beautiful thing I own.