In early 2019, Ian Davis lost 4 of his digits on his left hand to a work accident. His insurance did not cover his prosthetic. He was also diagnosed with Multiple Myeloma, an aggressive type of cancer, some time ago too, so things had been going pretty tough for him, but he was tougher it seems.
In an unfortunate accident he had in his own shop, his fingers were badly injured, doctors told him it's either your fingers or your life. "...being a maker, it was a tough deal,” Ian said as he had to use his hand for everything.
Insurance told him, to be eligible for a prosthetic you would have to lose your palm as well. So the fingers are "not medically necessary", you learn a new thing every day. Seeing there's no way around, he utilized his professional knowledge as a mechanical engineer and got into 3D printing to build his own prosthetics. He made and scrapped many models but he seems to have found a good ground to build on.
In a recent update on his YouTube channel, Ian announced that he's still making improvements and tweaks to his partial hand prosthetic. He recently added a "splay" functionality.
Ian happily decided to respond to some questions on Reddit after going viral. He said that this mechanical prosthetic is way better than electronic devices as "The motion is completely mechanical. And with that, fast! .2 sec to open or close the hand. Compare that with 2 seconds each direction on my Össur I-Digits Quantum. The other bonus is, mechanical never runs out of batteries and doesn't care if it gets wet."
Ian notes that he has never seen splay function in any other prosthetic too. Forward wrist motion closes the fingers on the device while lateral motion spreads them out laterally, or splays them, we could say.
The prosthetic Ian built has literally zero electricity need, it works with a set of elastic strings, rods, chains, nails a forearm rest, and whatnot. While the invention functions in its purely mechanical form, Ian also plans to implement an Arduino with a display to gain individual control of the fingers and some servo motors to advance the design.