From milk bottle houses to fungus headphones: See the Grand Designs on show in Birmingham

Kevin McCloud, who has fronted the popular BBC series for 20 years, says the world would be a poorer place if it weren't for people with bold ideas and a single-minded drive to make them a reality, even when other people scoff.

"We need these nutters prepared to put all their money in new developments, to let their imagination run free, and then to put it all on national television," he says.

But McCloud says that while the television programme is mainly about entertainment, he says many of the innovations exhibited at Grand Designs Live, which runs until Sunday, also point the way to a more sustainable future.

At the back of the hall, next to the stage, is Kevin's Green Heroes, a section dedicated to the presenter's favourite developments in eco-friendly technology.

It is here where you will find cutlery made from avocado seeds, spectacles made from potato peel, household tiles made from moss, and, yes, headphones made from fungus.

Plastic from sewage

"When you talk about plastic, people think about something made from oil, but you can make plastic out of bacteria, you can make plastic from sewage," says McCloud.

He says the potato-peel spectacles, made from a material known as 'chipsboard', could be a viable alternative to MDF, but is particularly excited by the headphones because they demonstrate a full range of textures and finishes, including soft foam-like materials, hard durable finishes, and leather-like coverings.

"Synthetic biology has finally grown up," he says.

The cutlery was met with approval from visitor Kim Hughes, from Worcester.

"Why hasn't it been done before now?" she says.

"Using up the leftovers from what's already out there to make something useful has got to be a good thing."

Milk bottle housing

One of the first sights to greet you as you walk through the door is a small house built from used plastic milk bottles, with its power supply coming from solar panels on the roof. The brainchild of architect Ricky Sandhu, it is made from 6,000 used bottles collected by members of a Sikh temple in Birmingham.

Ricky insists it is far more than just a novelty, saying he was in talks with a number of governments around the world interested in using the design to provide temporary accommodation for the homeless.

"The UK alone gets through 13.5 billion plastic bottles in a year, and spends £800 million clearing up ones that have been left lying around," he says. "By the year 2050, the weight of plastic in the sea will be greater than the weight of fish. This is a zero-carbon, zero-waste way of making use of those."

If you're feeling flush, you might want to splash out on the luxury lavatory devised by Redditch-based New World Bathrooms. But be warned, it will mean spending more than a penny.

The £1,900 'smart toilet' features a heated seat, self-cleaning jets, and a soft-closing lid, and does not require a cistern as it electronically pumps the correct amount of water straight from the supply. It can also be operated by remote control, if that's your thing.

Those who like the jet-set lifestyle will probably make a beeline for the Sky Pods stand, which provides a range of plush outbuildings made from slices of former aircraft fuselage.

"Sky Pods are a unique chances to own a part of aviation history, personal to you with an amazing story to tell," says the sales blurb. The model on display, which features an alluring electric fire, soft blue lighting and a large-screen television, costs about £25,000.

Mike Hyde says his cousin Andy got the idea when he saw a smoking shelter made from part of a scrap plane at an overseas airport. He says while it costs slightly more than a traditional construction, it does have its advantages.

"If you were building a conservatory or an orangery, you would be looking at the high teens," says Mike.

"But the beauty of this is if you move house, you can take it with you. You can use it as an office, a games room or a cinema."

Barravans

In a similar vein is the Garden Barrel, made in the Netherlands by CampPlus. The wooden-barrel style outbuildings are an easy way to create an extra room at your home, and are each equipped with a kitchenette, fridge and microwave, with a plinth heater meaning they can be occupied all-year round. Prices start at £11,000 for the duration of the show, and the company is also developing a 'Barravan' for those who fancy using their barrel as a holiday home.

There is a touch of the London Eye about the luxury garden seating in rotating glass pods on the Ornate Garden stand.

The rotating seater, tried out by visitors Rob and Vicky Osborne, normally costs £7,999, but is available with a £1,000 discount for those who buy at the show. But the Birmingham-based company will produce all manner of options for people who want something a little different – including one with a bed inside.

For a dash of indulgence, the Hydropool produces a 19ft spa pool for £35,000 to £45,000 depending on specification, while the Staffordshire-made Breeze House represents just about the last word in gazebo luxury.

Petrolheads will love the retro filling-station-pump furniture, which typically retails for about £3,000.

Rachael Hinkes of Custom Gas Pumps says the company originally started by supplying cabinets styled to look like old petrol pumps, but the range had since been expanded to include coffee machines and electric-car charging points. Rachael says the company typically sells between 30 and 70 a year, exporting them across the world, with car buffs and garage businesses among the customers.

People can also take a step back in time with the retro clocks produced by Penkridge-based Bad Dog Designs. Produced by Cannock man Paul Parry, the old-style digital clocks feature 1950s-style Nixie tubes. A simple clock is yours for £99, but if you want something a little bit special, the £6,000 clock styled to look like the Enigma decoding machine.