According to Wikipedia, the slanket – a wearable blanket with sleeves – was invented in 1998 by an American called Gary Clegg. Congratulations, Gary, but as regards this indispensable contribution to human comfort, Nicola L could rightfully claim to have got there first. The French artist, born Nicola Leuthe, had a cosy line in wearable artworks, known as pénétrables. Most are large, coloured canvases, hung on the wall with shaped sections into which you can insert your face, arms and legs. Others are rather cosier. Currently taking up substantial acreage at Camden Art Centre in London is the soft and fluffy Grey Rug for Five People (1975), essentially a family-size slanket.

The most appealing works in the show, titled I Am the Last Woman Object, hover between the worlds of art and design. These are jazzy, functional furnishing items made like body parts – freestanding bookshelves shaped like heads in profile, lamps like cartoon eyes, a giant foot that you can lounge upon, piles of cushions shaped like dismembered male limbs. A natty little ironing board – Woman Ironing Table #1 (2005) – features an iron shaped like a penis.

There is a delicately feminist flavour to this. The chests of drawers shaped like women’s bodies are titled La Femme Commode – which you can read as both “the chest of drawers woman” and “the accommodating woman”. Functional handles are positioned at both the nipples and the pubis. The Little TV Woman (1969) is a soft female figure, almost lifesize, with a screen in her abdomen that instructs us: “I am the last woman object. You can take my lips, Touch my breasts, Caress my stomach, My sex. But I repeat it, it is the last time.”

She may have made furniture by “cutting up” men, but Nicola L was no Valerie Solanas – the vibe here is good-humoured, even louche. In a publicity photo for an early exhibition, she stands naked embracing one of her vinyl-covered foot-shaped seats from behind. A film of her pénétrables being activated by a group of men was shot on a sandy beach and includes footage of them gleefully turning to display their bare bottoms.

Nicola L began making her pénétrables in the late 1960s. I am sure the sexual innuendo implied in art that you can physically penetrate was entirely deliberate. She was an active participant in the freewheeling counterculture, spending parts of the 1960s and 70s in Ibiza, and a substantial portion of her later life living at New York’s infamous Chelsea Hotel. Pénétrable, however, carries a further meaning, relating to understanding: conceptual penetration, being able to think your way inside something. Some of the pénétrables carry rallying slogans relating to equality, unity and environmental protection. “Same skin for everybody” proclaims a banner dressed with niches for 11 heads. “We want to breathe” says another.

Encouraging reciprocity and participation, her installation Fur Room is a purple plush environment, penetrable on all sides, including the floor and ceiling. The version shown here is a recent reproduction, and the furry-curious are invited to participate in the fluffy fun, choosing whether to insert their limbs into the lining of the room from outside, or to stand inside and interact with the purple body parts flailing at them from all sides. This goes down a bundle with children, who were having a great time being zipped into the floor compartments during my visit. Less so perhaps with Gen Z, impeccably dressed representatives of which were looking on aghast as they passed around the hand sanitiser.

As with the work of Yoko Ono, seen recently at Tate Modern, Nicola L embraces a sloganeering optimism, happily marrying pop and avant garde sensibilities and nonchalantly rejecting of the boundaries of genre. Her 11-person red coat (not on show) made its public debut on stage at the 1970 Isle of Wight festival during a performance by Gilberto Gil and Caetano Veloso. Video footage shows her “activating” a similar blue cape for a street performance in Cuba, and with a group of Chinese students at the Great Wall. Watching the students laughing as they are instructed to jump in the air as one makes this invitation to unity look fun.

It is interesting to have this shown in London concurrently with the Brazilian artist Lygia Clark at Whitechapel, whose brightly coloured, stitched-together costumes were produced in Paris in the same period. Both artists responded in their own way to the revolutionary energy of the times. Clark, 12 years older, approached the idea of relational art from a therapeutic lens, as a kind of healing or route to explore the self and its boundaries. Equally playful, L’s comparatively relaxed and intuitive work is an invitation to both adult fun and joyful protest. This is art of the street, the beach and the music festival.