Even the quickest visit to Jean-Christophe Aumas’s 10th-arrondissement flat in Paris immediately divulges a pulse-quickening array of influences: Here it’s flashy interior designer David Hicks, there sunbaked California, there Gio Ponti. Whatever whimsical drama Aumas has conjured in his home, a fun house of carefully curated bric-a-brac, splashes of unexpected color, and rare vintage furniture, he’s come by it honestly. As the artistic director of the creative agency Voici-Voilà, he designs store windows and special events for the likes of Louis Vuitton, John Galliano, Lacoste, Céline, and others. For Galliano, he once filled a window with a gigantic wave of shredded paper, and a display at the French department store Printemps involved live birds and sheep. The woolly quadrupeds were apparently well-behaved. “The only problem was they left the droppings absolutely everywhere,” he recalls.

Though Aumas’s kaleidoscopic 1,023-square-foot apartment may lack the scale of his professional projects, the surprising unity of the space’s design and decor, done entirely by Aumas himself, reveals a master’s hand—and the blurring of his professional and personal design pursuits. A number of colored cubes, created for a Sol LeWitt–themed Louis Vuitton display, are scattered across the living room floor, not far from a vintage Swan sofa by Arne Jacobsen. A Brick screen by Eileen Gray for Aram hides a tiny office. Color abounds almost everywhere you look.

In the living room, Aumas has painted one wall black with three blue triangles in the top right corner. Another wall is adorned with a pink rectangle underlined in yellow, a complimentary work of art by Aumas, and an eyeliner stroke of black that runs just beneath the cornice. “I like it when things are framed,” he explains. “It’s a trick I use a lot in my window displays.”

Ten years ago, Aumas was walking past and saw a for-sale sign out front of the building that once played home to royal stables under Louis XVI and that sits across the street from poet Paul Verlaine’s old abode. “A lady had lived there all her life,” he recalls. “There was carpet on the floor and really horrible wallpaper.” Still, he was immediately attracted by the generous ceiling height and the space’s typical Parisian charm. He promptly set about preserving as much as possible of the latter while giving the space a makeover.

“I look upon my apartment as a laboratory,” Aumas says.

Doing the design and much of the work himself, Aumas opened up the apartment to allow natural light to flood the rooms and replaced a solid wall in the bedroom with a glass partition. He also sought to preserve the herringbone parquet floor and original terra-cotta tiles (a number of which were simply painted black or replaced with geometric cement substitutes). The present-day kitchen was largely etched out of a guest room, and a former corridor became a walk-in closet.

The entry leads directly into the kitchen, where Aumas has created an installation of vine-like light fixtures, which he compares to a spider’s web. Move into the living room and find just the sort of playful vignette that abounds here: A stuffed fawn stands in front of the fireplace next to a disco ball and a pile of logs, whose ends the designer has randomly painted a host of bright hues. The photos on the walls are works by Aumas himself, and little knickknacks seem to get the same care as the oh-so-1970s brass dining table and chairs. A truly omnivorous design fan, Aumas ultimately places far less weight on boldfaced-names and storied manufacturers than on the piece itself. “I don’t care whether something is from a well-known brand or not,” he insists. “I can just as easily be drawn to something I find in the street as to something that costs a lot of money.”

Perhaps the most fertile ground for Aumas’s whirling collection of stuff is its owner’s travels. In the living room is a coffee table acquired in Palm Springs, California; a rock crystal from Los Angeles; a resin apple he picked up in Tokyo. More than anywhere else, though, Aumas loves the hunting in Belgium. The Charlotte Perriand stools in the kitchen were unearthed in Antwerp, the dining chairs are from the showroom Dune 234 in Brussels, and a giant photographer’s lamp comes from the Jeu de Balle flea market in the same city. So as not to live entirely in the past, Aumas has added into the mix more recent designs, like Tom Dixon’s Slab coffee table and a golden, Formica console table of his own devising in his office area.

“I look upon my apartment as a laboratory,” Aumas says. “I can buy a new piece of furniture and rearrange everything around it.” Ever in a state of transforming his home, Aumas recently ordered a minimalist black leather sofa from the Italian brand Progetto Domestico and is even contemplating a more serious overhaul. “I want something more conceptual and pared down,” he reports. Just how spare the result will be is anybody’s guess. As Aumas himself admits, “The problem is that I really love objects!”