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When Jacob was born eight weeks early most of his left arm was missing.
His parents Gemma Turner and Chris Scrimshaw, from Calderdale in West Yorkshire, crowdfunded to get a £16,000 functioning limb made for him.
The NHS and most companies take the view that a functioning prosthetic is not an option when the limb ends above the elbow.
That is where Ben Ryan, from Menai Bridge on Anglesey, came in, designing an arm for Jacob, who is now five.
Mr Ryan developed a hydraulic design after his son Sol had an emergency amputation when he was 10 days old.
It led him to quit his job as a psychology lecturer and set up his own company, named Ambionics, two