The internet has transformed T-shirt design into a booming cottage industry for designers and illustrators. Submission sites that convert humble Illustrator files into wearable, screen-printed designs are flourishing, while anyone hoping to set up as an independent label can use the web for all aspects of business, from sourcing to sales.

But the technology is only part of the picture. Creative professionals wouldn’t be so keen on T-shirt design if it wasn’t worth their while. So what makes it so attractive?

“I work in creative services, so I’m doing a lot of design both for the web and print every day,” says New York-based designer Andrew Gregory, who works under the name Lunchboxbrain. “The long and short of it is, designing T-shirts is a way for me to be a little bit more creative than I was doing in my nine-to-five work.”

“I think the thing I like the most about it is the creative freedom,” says Matt Lyon, who works as C86. “I can test ideas out. I can experiment, whereas if you’re doing commissioned work, people are coming back and asking you ‘can you change this? Can you do that?’ This is my leisure time. I can do what I want.”

International community-based sites like Threadless, Design By Humans, Shirt.Woot and others also offer the chance to earn money. Creatives submit their designs, and community members then vote to pick their favourites. The most popular designs then win cash prizes –which can reach thousands of dollars. Popular designs also get made into T-shirts. Done right, it’s possible to earn a living solely ‘subbing’.

“Lately I’ve been making a living more from T-shirt design contest prizes than commissioned freelancer work,” reports Matheus Lopes Castro, who designs as Mathiole, who is based in Brazil. “I think I win at least once a month – that’s my goal, actually. Sometimes I win more, and other times I win nothing.”

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So what makes a successful T-shirt design? Well, you can’t go wrong with a reference to popular culture – especially with some sort of pun, whether it’s visual or text-based.

“Whenever the [creative] well is dry, I always think, what’s a good pop culture reference that hasn’t been done before?” reveals Andrew Gregory.

But that’s not to say that you can just pull out a clever swine flu gag and automatically top the submission sites. Others argue that the most important aspect of a T-shirt design is a bold, striking and immediate image – which isn’t as easy as it sounds.

“Compared to a normal piece of artwork, it takes quite a bit more simplification,” says designer Matt Lyon, who trades as C86. “It’s more to do with the focus, the impact. A T-shirt needs to be instant. If someone’s wearing [a design], they can’t be at the other side of the room and it just looks like a blur.”