It wasn't so much necessity as trash that was the mother of invention for Hiram Esparza.

"My wife was about to throw away an empty can of protein shake," Esparza explained Sunday outside the fifth-annual HACKMemphis at the FedEx Institute of Technology on the University of Memphis campus. "I said, 'no, don't throw that away,' and I began accumulating them until I now have four."

Enter Sunday's hackathon event, which brought Esparza together with colleagues Ashlesh Gawande and Jesus Arana to prove Esparza's wife wrong when she said he'd never do anything with the empty containers.

By the time the project demonstration period rolled around at the end of Sunday's weekend-long event, Esparza and his partners had transformed an empty container into a R2-D2-like robot, complete with a camera that can be used for surveillance or any purpose a user might want.

That's exactly the kind of creative thinking HACKMemphis hopes to inspire with its event each year, said organizer Claudio Donndelinger.

"Over the span of a weekend, we sort of force people to work together," Donndelinger said. "It's a very free-form event. Typically, amazing things happen."

The robot was only one of many creative projects developed by teams over the weekend. Other projects demonstrated at Sunday's close included a program allowing visitors to identify customers in their store at a given time by their auto license plate so the business can better cater services to them; an application allowing users to locate food trucks and read reviews about them; and a game to make working out on a stationary bike more fun.

Participants were primarily engineers, programmers and developers. Many said it the event provides an escape from their jobs so they can work on projects of their own choosing.

"It's just a chance to meet up with like-minded people," said Scott Umsted, who developed Turnstile, the program that tracks license plates.

Umsted, an enterprise architect at FedEx, said he's been to HACKMemphis for four years and always enjoys the mix of people.

Kevin Nuckolls attended with his daughter and friends and used the occasion to give the girls a chance to work on coding skills.

"Coding is a super power," said Nuckolls, director of engineering at Mosaik Solutions. "If they can grow up and have the ability to have a super power, there's no reason not to. Programming is valuable in any field."

Donndelinger said more than anything, the event is just a way for people to hone their skills and network. The event grew from about 30-40 participants to more than 100. The U of M has provided the venue most years, but AutoZone and several others served as this year's sponsors along with the university.

"People come here, and they connect," Donndelinger said. "They find answers to questions they didn't even know they had. That's the beauty of it."