James McCormick, 56, was convicted on three counts of fraud at London's Old Bailey courts after jurors were told that the bomb detectors, which resembled car antennas, just did not work.
The devices, which he sold to governments around the world, had no connected parts and no power source.
The former policeman and salesman sold the top-of-the-range ADE651 fake bomb detector for up to $40,000. The novelty golf ball finders were on sale for $20.
British media reported that McCormick claimed accompanying sensor cards could be slotted into the Advanced Detection Equipment units to enable them to search for explosives, drugs and people.
McCormick sold his equipment to the Thai army, to help fight the violent counter-insurgency in three southern provinces, Yala, Pattani and Narathiwat. About 800 of the GT-200 models were bought for 550,000 baht each.
A Phuketwan reporter saw one of the bomb detectors being used to scan the Phuket roadside before an important Asean conference featuring then US Secretary of State Hillary Clinton took place at Laguna Phuket in 2009.
Pakistani forces used it for airport security, the Mexicans used it in murderous drugs wars, the Lebanese waved the device in protecting hotels in Beirut.
''I never had any negative results from customers,'' McCormick told the court.
The fake bomb detectors he sold to the Iraqi government for $85 million were inevitably useless. Massive kickbacks worth millions of dollars had been handed out to Iraqi officials, the Independent newspaper reported.
According to the Independent, the companys' sales literature claimed the device could ''sense'' minute quantities of incendiary material from a kilometre away on land and three kilometres away from the air.
It could also track down a variety of other items including various fluids, ivory and people who had hidden themselves.
They were able to operate, McCormick maintained, through walls, underwater and underground. It was, he would declare in his sales pitch, truly a miraculous piece of engineering which could detect anything ''from explosives to elephants.''
McCormick was trained at a ''how to sell to the UN'' seminar organised by UK Trade and Industry in March 2008, the Guardian reported.
Whistleblowers reported that the devices did not work. Their advice was ignored by British government departments. ''Clearly people were dying as a result of the use of this product,'' one person who warned the government told the Guardian.
An Iraqi bomb victim described McCormick to the BBC as a ''morally bankrupt'' man.
BBC Two's Newsnight program conducted an investigation into the devices, resulting in a government ban on their sale in Iraq and Afghanistan in January 2010.
McCormick is to be sentenced on May 2.