Old trolleys, lawn mowers and water drums may not seem like much but they have become tools of the trade for a local start-up.

Using these items and more, Bikes 4 Fun has given old, unwanted bikes a new lease of life.

Among its creations: a lawn mower bicycle which can cut grass during the ride, as well as a "train trike" bicycle which tows additional seats made of connected old trolleys and water drums.

These will be among 50 novelty bicycles on display at the Singapore Science Festival's Maker Faire in Tampines Street 11, an event organised to showcase creative projects in areas such as science and technology over the weekend.

Bikes 4 Fun's manager, Mr Mostapha Kamal, 28, said that through his bicycles, he hopes to show children the value of reinventing and being creative.

"I wanted to show kids that recycled bikes can be a lot of fun. Sometimes, all they need is a fresh coat of paint," he said.

The idea for his business first came about in 2006 when Mr Kamal, who studied earth architecture, was working in Cromwell, a town in New Zealand.

The father of two boys, aged three-year-old and nine-months-old, noticed that kids there often spent their time outdoors. He started collecting old bicycles that people had thrown away and giving them a makeover.

And he returned to Singapore in March this year with some 100 bikes, which are kept in a container in his Kaki Bukit workshop.

Mr Kamal said his ideas come mostly from children themselves. The train trike bicycle, for instance, was built for his three-year-old son who wanted a "choo-choo train". His other creations were born from fiddling with old, discarded items such as water pumps and blenders, or were adapted from other designs.

For instance, he drew on the design of the Penny Farthing, one of the world's earliest bicycles with a giant front wheel and a tiny back wheel, to create a similar-looking "Penny Fake Thing" from a mountain bike frame.

Bikes 4 Fun rents out these bikes at school, community and corporate events.

Last Sunday, the company organised an event for about 400 children at Clementi Primary School.

"Children love bicycles," said Mr Kamal. "It's very hard to find kids who don't love them."