"One of the challenges he set before he died was to make New Zealand predator free.
"I'd been thinking for a long time about what I could do -- and the conservation awards presented the opportunity to actually get something ready."
Mr Hart spent 15 years in the technology industry, but has recently taken to inventing mechanical devices of his own.
So far, as well as the Kei Te Pai, he has created a 3D printer, an unmanned aerial vehicle for mapping rivers and a sensor system to monitor water levels -- with the aid of a small open-source computer, called the Arduino.
"A friend had a spare starter kit, and asked if I wanted to borrow it -- and I got hooked.
"When I'm on long drives, I'm often thinking of new ideas, or stuff around home I can fix up."
Mr Hart designed the Kei Te Pai trap to continually re-boot itself by way of a solar panel, converting sunlight to mechanical energy.
He said existing modern possum traps are able to re-set themselves with a gas cylinder -- but only last a matter of months, requiring trappers to travel extensively to replenish them.
"One of the biggest problems in pest control is the human cost," he said.
"The Kei Te Pai can remain active for many years, and removes the need for extra labour, especially in hard-to-reach areas.
"It doesn't put anything harmful into the environment -- the mechanical energy pings the possum, and the trap re-sets."
The trap would also make use of pheromone-based baits and electronic sound lures to attract possums from further away, eliminating the need for toxic baits.
"If we could get rid of things like 1080 tomorrow, I'd be a happy camper."
If the Kei Te Pai is developed further, Mr Hart plans to keep his design "open source" -- meaning anyone can work on refining it.
"I didn't want it locked into a patent," he said.
"I'm all about sharing ideas, so they can be explored and improved upon."
The winners of the Conversation Innovation Awards will be announced on November 5.
