Thrill seekers can drive life-size Tonka toys and move massive mounds of earth thanks to Ed Mumm's $1-million heavy- equipment theme park in Las Vegas. Visitors operate either Caterpillar D5 track-type bulldozers or CAT 315CL hydraulic excavators in a five-acre sandbox.

"Dig This," as it's called, has brought construction to the masses. "It gives people a real appreciation for the industry and what it takes to operate this equipment," says New Zealand-born Mumm. Indeed, Dig This has become an instant smash hit, especially among grandmothers and housewives. "Half our customers are females. Throttling up a powerful engine and moving mounds of earth is very empowering," says Mumm.

Dig This is ranked as Las Vegas' top attraction out of 491 entertainment choices, according to "I have always been enthralled with watching construction sites in action," wrote online reviewer Cathy K. of Cupertino, Calif. "Being able to operate an excavator by myself was more fun than I can say."

Mumm is franchising the idea, with another Dig This set to open soon in Sydney, Australia. "The program has been very successful, but there were a lot of unknowns to get this going," says Mumm, who previously ran a fencing company. "It took us a year of searching just to find insurance." A Dig This pilot version ran for three years in Steamboat Springs, Colo., giving Mumm time to work out the kinks before opening in Las Vegas last April. Mumm accidentally stumbled upon the idea while digging a well with a rented excavator at his Colorado home.

"I really began having fun," says Mumm, who holds an agriculture degree. "I thought other people might enjoy it, too. Nothing like this has ever been done before. It was a hell of a risk."

Mumm's gamble has paid off. Dig This has garnered national attention and a growing fan base. "Freaking awesome! We can't wait to go back again and dig some more," writes another online reviewer, Doug P. of Las Vegas. "In fact, we are thinking of a career change."