A proper one should be stylish, with proper straw, lightweight and aerodynamic, but strong enough to withstand a few collisions.

The 21-year-old science student has made a sideline out of crafting brooms after taking up Quidditch, the fictional wizard sport adapted for the real world by a community of Harry Potter devotees.

The brooms don't fly unaided, but are held between the thighs of players as they run around on fields, hurling and dodging balls in line with a complex, slightly bizarre set of rules.

"I didn't want to run around with a stick between my legs," said Mr Downes, whose brooms cost between $25 and $140.

"If I was going to play Quidditch I was going to do it properly."

Mr Downes, trading as Keymaster Broomstick Industries, was at the University of Wollongong on Thursday for International Harry Potter Day, which celebrates the work of author J. K. Rowling.

It is timed to coincide with the date Potter defeats the villain Lord Voldemort in the final book of Rowling's series.

Members of UOW's Harry Potter Society yesterday converted a section of the campus into Diagon Alley - a cobbled shopping precinct within the Harry Potter universe.

They served up plastic cups of butter beer - a mixture of cream, butterscotch sauce and brown creaming soda - and offered interested passers-by the chance to pose with tapestries from the four houses of Potter's school.

Visitors were offered a wand - a jumbo chopstick lovingly styled with clay and painted by UOW's self-styled wand maker Ezekiel Azib.

"You do not make the wand; the wand makes itself," he told the Mercury.

Society president Kurt Rallings said the day was a way to continue the magic of Potter's world.

"We've grown up with them," he said. "This is a way to keep the world going now they've stopped."