Some students sell fluids, others pile into focus groups to cushion their spending habits over the holiday season. And Phil Doherty made cash while he was in college in Florida by selling his skills.

“I’ve been knitting since forever . . . I’d knit during class. It helps me concentrate, so I ended up with all these extra hats and scarves and stuff, so I sold them. I didn’t make much, but it gave me some extra money,” he said.

Florida proved the perfect venue for his winter wears.

“It can get chilly in Kissemmee in the winter, so I had a lot of freshman coming to me for hats,” Doherty said.

Entrepreneurial endeavors like raking, shoveling snow, knitting and selling lemonade are more straightforward ways of making money on school breaks, Doherty explained.

“You realize that when you’re like twelve,” he said. “But it’s a lot of work for very short return.”

So some people subvert the system and sell bits of themselves instead. Kris Bentley (not his real name), a senior at the University of Utah, sold his plasma to buy his books last year.

“It’s like $70 for your first time, but afterward you get about $40 for each visit. I went whenever I could find someone to drive me, and made like $1200 last year doing it. I saw the Lethal Weapons more times than I can count,” Bentley said.

While getting the repose to watch old macho movies can one upside to donating plasma, Bentley admitted scarring is a real possibility and became the only flaw in his money making scheme. The process is kind of like going on dialysis, and Bentley ended up with a scar on his arm from his foray into selling elements of his blood.

The machines take at least an hour to draw enough plasma to warrant the $30 – $40 cash incentive, and the process is not exactly pleasant, Bentley explained. But he hasn’t quit doing it.

“I’ve got debts that won’t disappear on their own,” he said.

In Boston there’s a plasma donation center on Boylston Street in Chinatown. Others can be found on Google. A first donation requires a good amount of paperwork and a blood test, so it can take four to five hours. But once the blood donation center has the initial information, subsequent visits are fairly fluid.

When Bentley realized his juices sold, he became insatiable.

“I looked into selling my sperm, but I’m too heavy. They wouldn’t even interview me,” he said.

But you don’t need to sell fluids to make fast money. Some college students sell their ideas.

Moriah Nelson, a Senior at Loyola University in Chicago, made extra cash by participating in research projects. She has been on both sides of the process.

“A lot of research is done through grants. And there are a lot of non-profits in Chicago [and Boston] who want to have a study done for their programs, so they write a grant and we do the research . . . Some people get paid to do the research, but most just volunteer,” she said.

It takes some effort to make money on the research side of student studies, but being guinea pig can pay tens of dollars, and its fun.

“Being in a focus group was interesting. I found the one I did on Craig’s List. They got a bunch of college students and wanted to get student’s opinions. It took about an hour and we got twenty dollars,” she said.

The travel time and costs can detract from the cash benefits, she admitted, but studies are a great way to get overcome boredom and pay for a movie ticket.

“It’s fun to hear other student’s opinions. All I had to do was call in and meet their qualifications. Then they gave me a time to show up, and as long as I could make it I was in,” she said.