Matt Denton, from Hampshire, estimates his "very expensive toy" has cost him hundreds of thousands of pounds.
He says a mining company and a marine research organisation are now interested in his design and he hopes it might be used at science fairs.
During its development the machine had one outing, at a music festival, where Mr Denton says it was well received.
"It's an entertainment vehicle," he said. "But I hope it will inspire people."
The project was only initially intended to take 12 months, Mr Denton, who usually specialises in small-scale animatronics for the film industry, said.
"After 18 months we tried the model out. We had to completely strip out and rebuild the legs. They were too heavy and complicated.
"I'm a software and electronics engineer so this was out of my area - I had to learn fast."
The robot, driver-operated by joysticks within a cockpit, can only travel at 1.5km/h (1mph) and manage a distance of 5km on a 20-litre (4.5-gallon) tank of diesel.
"It's not about miles to the gallon, it's about gallons to the mile," he said.
"It wasn't built to be efficient and fast. It was built to look cool and insect-like and fun."
Mr Denton said he was inspired by science fiction to create the "walking" machine.
"But legs are very inefficient - the wheel was invented for a reason," he added.

The QPR defender, 36, released a statement saying his "wonderful wife and soul mate" Rebecca Ellison had "passed away peacefully" at a London hospital.
Ms Ellison, 34, who married Ferdinand in 2009, had breast cancer.
She leaves behind three children, Lorenz, nine, Tate, six, and four-year-old Tia.
In a statement, Ferdinand said she died on Friday night.
"Rebecca, my wonderful wife, passed away peacefully after a short battle with cancer at the Royal Marsden Hospital in London," the footballer said on QPR's website.
"She was a fantastic loving mother to our three beautiful children. She will be missed as a wife, sister, aunt, daughter and granddaughter. She will live on in our memory, as a guide and inspiration.
"Myself, my parents Janice and Julian, along with Rebecca's parents Lesley and Stephen, would like to thank our families, friends and my club colleagues who have rallied around in these desperate days, weeks and months."
Ferdinand thanked the staff who treated his wife at the south London hospital, adding: "I would also like to express my gratitude for the dedication and expertise of the staff led by Professors Johnstone and Clark at the Royal Marsden.
"Their valiant efforts to prolong Rebecca's all-too-short life will not be forgotten."
Messages of support have been posted on Twitter from the world of football.
Former Manchester United goalkeeper Peter Schmeichel wrote: "Really sad news that Rebecca Ellison, the wife of Rio Ferdinand has passed away. My condolences to Rio, their children and the family. RIP"
BBC presenter and former England captain Gary Lineker tweeted: "Thoughts are with Rio Ferdinand and his family. How dreadfully sad."
In a statement, the west London club said: "The thoughts of everyone at Queens Park Rangers Football Club are with Rio and his family at this immensely difficult time."
Manchester United said: "Everybody's thoughts at #mufc are with Rio Ferdinand today, whose wife sadly passed away last night."
Ferdinand, who grew up in Peckham, south-east London, was capped by England 81 times and has also played for West Ham United and Leeds United.
Both sets of players wore black armbands in QPR's match against Liverpool at Anfield, which the home team won 2-1.
When Leroy Fer scored in the 73rd minute, he lifted his shirt to reveal a "stay strong family Ferdinand" message.
Other team-mates also tweeted their condolences.
QPR captain Joey Barton posted: "Just heard the terrible news. RIP Rebecca."
Goalkeeper Alex McCarthy wrote: "Devastating news about Rebecca Ferdinand... My thoughts go out to him and his family."
A giant-mantis robot with hydraulic legs has been unveiled by a designer who spent four years creating it.
[NEXT_CONCEPT]
The wife of former Manchester United and England captain Rio Ferdinand has died from cancer.