When engineer Mat Bowtell was retrenched from his car manufacturing job with Toyota in October, his life took on a very different path.

He splurged his redundancy payout on 3D printers and set up shop in his "man cave" on Phillip Island, 150 kilometres south-east of Melbourne, designing and making cheap prosthetic limbs.

Mr Bowtell, 38, said his lightbulb moment occurred in 2004 when he was studying mechatronics with Monash University on a scholarship in Japan.

"I tried on a $1 million bionic arm and I just thought 'Wow, this is really, really fantastic technology, but who on earth is going to be able to afford it?'" he said.

With the help of crowdfunding, Mr Bowtell now has 12 3D printers in his workshop, along with prosthetic-grade scanners and sophisticated software and equipment to make the limbs that he gives away for free.

"A lot of the things I design you can basically just strap them on," he said.

"The free licence allows people to take their own measurements and scale it themselves and print their own out."

Lois Agnello, 6, can now ride her bike after being fitted with her first prosthetic hand. ( ABC TV: Catalyst )

Passion for helping children

Mr Bowtell recently provided Lois Agnello, 6, of Bass with her first prosthetic hand.

"I took her measurements on a Friday and was able to give her the hand on the Sunday," he said.

"So it really only took a day, whereas commercial, traditional techniques can take months."

Mr Bowtell mostly makes hands and has just released a design for partial finger amputees.

Victorian engineer and prosthetic limb designer Mat Bowtell with Catalyst presenter and surgeon Nikki Stamp. ( ABC News: Amy Sherden )

"If you've chopped off your finger you're able to get full function back, and one of my friends in Japan was actually able to play the piano again, and it costs about 90 cents to make," he said.

He also designs and makes assisted devices including skipping rope adaptors for children such as Lois, who was born with only part of her left hand.

"It allows kids to join in and do things with all the other kids at school, things that we take for granted like riding a bike, helping mum and dad with the dishes and playing drums," Mr Bowtell said.

His designs carry a creative commons licence that allow people to download, but not sell or profit from them.

Free limbs have saved estimated $6.5m

Mr Bowtell distributes the prosthetic limbs for free thanks to crowdfunding. ( ABC TV: Catalyst )

The Victorian Local Hero Award recipient said he had sent prosthetics all around the world and recently sent a new hand to a girl in Iraq.

He lets children choose their own colours and designs, and said making the limbs for free was incredibly rewarding.

"It's very emotional to see someone receive their hand for the first time," he said.

Mr Bowtell said his designs had been downloaded more than 1,000 times, saving people an estimated $6.5 million.

"It can cost $15,000-plus for a commercial prosthetic and kids grow out of them so quickly," he said.

"I don't charge for what I make, I don't even charge for the postage, and the way I'm able to do that is through crowdfunding.

"I think as a society we need to look after people who are disadvantaged or have disabilities or limb difference.

"If you give something worth $100 to someone then it's only worth $100, but if you give it to them for free it becomes priceless."

See more on this story tonight on ABC TV Catalyst at 8:30pm or on iview.