At a workshop in Seine-Saint-Denis on the outskirts of the French capital, some 20 costume designers and milliners were hunched over their creations during a recent visit by AFP.
It is just one of around 20 workshops dotted around France, humming with the sound of sewing machines and piled high with rolls of fabric and props a month ahead of next month's Games.
Costumes were hung on the racks but were covered with a tarpaulin to preserve the surprise.
"We are creating the biggest party in the world," said Daphne Burki, 44, director of costumes for the Games, who previously worked under John Galliano at Dior.
Some 15 designers are involved in the preparations, overseeing around 500 craftspeople who are working on the opening and closing ceremonies for both the Olympics and Paralympics.
There will be some 200 dressers and nearly 300 hair-and-makeup artists in place just for the first ceremony on July 26, which is taking over a seven-kilometre stretch of the River Seine and its bridges.
In an era of mounting concern over clothing waste and pollution, there is a lot of emphasis on using vintage and second-hand outfits, "which had a life before and will have a life after", said Burki.
"You will see 3,000 unique silhouettes," she added, vowing that no two costumes will be the same. "Each garment tells a story."
One of the few outfits shown to AFP combined a medieval doublet jacket with a tracksuit cut in neoprene and stretch cotton -- "a reference to both fencing and the history of costume", said Olivier Beriot, Burki's deputy.
"We played with all the historical shapes and mixed them with today's materials," he added.
In the workshop, Roberta Oakey, 59, a former costume designer at the Paris Opera, is working on the fabric for a dancer's costume, for which she must ensure "maximum movement".
Another costume designer, Corinne Page is trying to give "more hold" to another outfit.
With more than 30 years of experience in theatre and opera, she is used to the complex work, which often requires making, remaking and reassembling outfits multiple times.
"But we love it!" she said.
The team "only sees one end of the lens" of the ceremonies, she added, "but it will be spectacular."
