The shelter can withstand storms, extreme cold, and even bullets

Its creators were on BBC TV's Dragon's Den, but they refused investment from the show's entrepreneurs because they wanted too much of their company.

Will Crawford and Peter Brewin's design will go into production at their new plant near Pontypridd next summer.

It is made by adding water, pumping it into shape and waiting for it to dry.

Their "concrete canvas" shelters have already drawn interest from aid agencies and the military.

"We originally came up with the idea when were entering loads of design competitions to fund our way through college," said Mr Crawford.

"The concrete cloth is inspired by the material used to make plaster casts in hospital, but we had to come up with a completely different way of making it work with concrete."

The "dragons" actually offered us the money we wanted, which was around £85,000

Will Crawford, Concrete Canvas

Along with his friend from Imperial College London, Mr Brewin, the two 28-year-olds turned the concrete cloth idea into a way of putting up cheap, long-lasting emergency shelters.

The shelter is delivered in a bag, which is ripped open and water added.

The material soaks up the moisture, activating the concrete. But the cloth remains flexible and is inflated by a battery-operated pump.

After 12 hours, the shelter becomes completely solid, and can even withstand being shot at with handguns.

"One of the competitions we entered helped to fund us to go out to Uganda for five weeks where we spoke with aid agencies and non-government organisations on the ground," said Mr Crawford.

"That really encouraged us to pursue the idea of the shelters."

The two inventors were so confident in their product they showcased it on the BBC's Dragon's Den, where entrepreneurs bid for funding from real-life millionaires.

"The 'dragons' actually offered us the money we wanted, which was around £85,000," said inventor Mr Crawford.

"But they wanted 40% of the company for that investment, and that was simply too much for us, so we walked away."

However, the shelter idea did not go unnoticed and the pair won development funding from the Department of Trade and Industry, and a regional assistance grant from the Welsh Assembly Government.

It has led to them setting up their production base at Treforest, near Pontypridd, with full-scale production starting in eight months.

The entrepreneurs have already sold a shelter to the US military to be assessed, and they will fly to America in the new year to give a demonstration to the US Naval Construction Force and federal emergency planners.