Sales grew quickly, and Invisibobble went international in 2013. Pairing up with distributors around the world, the firm started shipping to 12 countries.

Although the company was growing, Sophie says: “People were initially really dismissive of my product. I was laughed off because it was ‘just a hair accessory’.

“My flatmates would laugh at my Instagram posts about the business, or if I was creating an invoice on one of the uni computers.”

But by the time Sophie’s graduation rolled around in 2014, Invisibobble had an annual turnover of more than €6m ($6.6m; £5m).

“People still couldn’t believe that Invisibobble could be a full-time job for me.

“In my final year, the careers counsellor told me to apply for jobs in HR after she found out that I wanted to work solely on my business.”

Sophie noticed a shift in 2016, after she and her business partner Felix were listed on the Forbes Under 30 European entrepreneurs in retail list.

“That’s when people started taking us seriously,” she says.

Sophie says this is the moment when Invisibobble really started “strategising”.

“We put a product on the market, and it was a hit. It felt super-weird. But we had never taken a moment to step back and think about the bigger picture.”

A few instances of Invisibobble being copied caused Sophie to change tack. “In every market, the same thing would happen,” she says. “We’d overperform, then another label creates a cheaper version.

“Now, it’s too risky to just come up with an idea in the shower. We have to be the most innovative hair accessory, and we have entire teams developing the coolest products or campaigns.”