This is Business Daily on the BBC World Service. I'm Wiltshaw, and today we're looking at the ultimate form of fancy dress.

So it's actually freely printed, and I had someone who I know who works in electronics who worked with the mechanism to make this thing move.

No, it doesn't. Oh my. When you press a button, the blade swim around.

Yes, that's right.

I'm in central London at a convention centre,

surrounded by thousands of people like Denji,

in the most elaborate fancy dress you will ever see.

They're all cosplayers.

If you've not heard of it,

it's where you dress up as a fictional character

from a graphic novel, animated TV, show or video game.

Usually, as in Denji's case, it's a costume you've made yourself and invested a lot of time into it.

So how long did this take?

So 3D printing, this whole helmet took around one month and then painting it another two months

and then it took up to six months to work on the mechanism.

So it could be around 10 months.

As well as being entertaining for those taking part,

cosplay is also a big money spinner.

With conventions like this, where people come to show off their costumes,

common across Europe, the US and East Asia.

So, what's the fuss?

Well, in today's program, I'll be finding out how the hobby is increased in popularity over the past 20 years.

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