Now in its sixth year and incorporating at least 250 shows, the London Design Festival has become a fixture on the international design calendar. But this isn't because it competes with the vast Salone Internazionale del Mobile, held in Milan each April. No, what characterises the UK capital as a design centre is its focus on ideas rather than production. The city's young innovators are experimenting with processes, techniques, materials and styles and showing off their latest work this week.

Matthew Plummer-Fernandez

Plummer-Fernandez, who was born in Colombia, started blending industrial techniques with musical skills when he was studying mechanical engineering at King's College, London. His Sound/chair, on sale for £3,950 at Designersblock's pop-up shop at Selfridges during the festival, began as a sound, drawn on a graph using volume, time and frequency plots; the shape was then crafted into a chair made from water-jet-cut polyethylene. The designer has also created a neon light, on show at Designersblock in Covent Garden, using sound waves; the shape and size of the case corresponds to the buzz emitted by the light. He calls it a "sound sculpture".

"A lot of things in life today are intangible - downloading music from the internet or using a credit card - and bringing something intangible back into the material world fascinates me," he says. When Plummer-Fernandez graduates from the Royal College of Art next summer he aims to work on big public installations. He is already decorating one of Selfridges' windows for the festival. Called "The Apifera" (a botanical term referring to the attraction of insects by flowers), it involves 200 variously shaped, iridescent blue cards installed to create a spiral pattern similar to a flower's interior. Each segment is backed by a fan, causing it to flutter; its motion changes depending on the weather, the time of day and the movement of passers-by. "These pieces aren't just artworks; they can be functional too," he says.www.plummerfernandez.com

Steve Watson

Australian Watson moved to London in 2003 "to be at the centre of the design world" and works in Hackney. His Milan SaloneSatellite show earlier this year attracted attention but he has yet to sign up with a manufacturer. "It's incredibly challenging to push the boundaries of design while being commercial," he says.

His Skase teacup (a white glazed cream-ware cup with a pointed shape that sits on a walnut cross-base) will sell for £25 at the Selfridges pop-up shop. And he is showing three pieces at Designersblock in Covent Garden. Cassiopeia is a glass-topped dining table with a cold-rolled aluminium base formed from three laser-cut pieces braced together in an elliptical pattern so it looks different from every angle. His curvy Rakel bar stool is, by contrast, technically simple but innovative because of the removable "corset" made of lace, satin and velvet on its chrome-plated steel frame. Finally, the Prop table-lamp is made from a laser-cut and moulded acrylic sheet. "I need to get the moulders to reverse their normal procedure by first cutting the shape then forming a curve," he says. "This is a more efficient process and cuts waste."

His next endeavour? Turning lace stockings into chairs or coffee tables.www.steve-watson.com

Jordi Canudas

Originally from Barcelona, Canudas studied industrial design at Elisava Design School, then moved to London in 2004 to work in a studio. After graduating from the RCA in 2007, he joined with eight fellow students to form the Okay collective. The designers operate as colleagues, generally working on their own projects but sometimes collaborating on client work and exhibitions, including a new group show called Under The Same Roof at London's Aram Gallery.

Canudas is creating an installation experimenting with chocolate and light. Spotlights projected on the chocolate cause it to melt and drip on to other lamps. As it slides down their sides, it gradually obscures the illumination, acting as a shade. "I like ephemeral things that are here one moment and gone the next, which is why I like working with light," he says. "I'm also interested in reactive materials; chocolate has very malleable properties."

Lesslamp, now produced by Spanish manufacturer Metalarte and presented this year at the Kettal showroom, is similar in that it releases light only when broken. An egg-shaped, lacquered ceramic shell is cracked with a specially designed pick so the final shape is created by its user. To make it, Canudas injected plaster inside a balloon, rotating it by hand so it only stuck to the walls; when set, he tore off the latex to reveal a thin, yet strong, shade. "The lamp has a beautifully smooth finish and I really enjoyed creating a design that uses such a simple process and materials," he says.

His experiments with stretch fabrics have meanwhile led to Wallfa, a piece of furniture that doubles as a wall and sofa.www.jordicanudas.com

Tomek Rygalik

Rygalik studied architecture at the Technical University of Lodz, in his native Poland, then industrial design at New York's Pratt Institute before enrolling in the RCA. He now runs his own practice in London's Portobello Road and in Lodz and teaches at Warsaw's Fine Art Academy.

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"My designs are practical but all have an experimental ingredient," he says. "I start from an idea rather than an aesthetic and I don't do anything for decorative effect. Often it's a conversation with the material rather than imposing a form on it. The material drives the design forward."

He cites his self-supporting Raw armchair for Moroso, in which the structure stems from the way the leather is sewn together. "It looks sculptural but every stitch is there for a reason," he says. Another example is his eco-friendly outdoor chair for Artek; he opened up the ergonomic shape by slitting the plywood before it went into the mould.

About 60 of Rygalik's re-configurable Lampudra lights, inspired by industrial engineering, and his Termo modular seating system for Noti, re-configurable to seat one, two or three people, will form an installation at Poland Street Underground at Soho's Vinyl Factory. A prototype bathroom will be displayed at the RCA's Living Proof show. Each element has innovative functions: the basin has flexible taps and an extendable surface; the mirror displays the user's weight; and the height-adjustable lavatory has a super-sized seat (for obese people).www.tomekrygalik.com

Julia Lohmann

Lohmann, who hails from Germany, was one of four winners of the Design Miami/Basel Designer of the Future award this year. Her best-known designs are her lifelike leather Cow bench and the Flock and Ruminant Bloom - lights made from preserved sheep's stomachs.

Her designs are driven by "a big fascination with the natural world and a curiosity about how things work and how I can use that to make something different", she says. "They start with materials that haven't fulfilled their potential and experiments with how they can be used in different ways, or they start from a process that I'll use in a new way. I love collaborating with specialists in a field unknown to me and exploring processes that haven't been used for design."

Recent experiments have resulted in chandeliers whose frames and shades are encrusted with crystallised salt. "Chandeliers are normally very expensive so I've taken a humble material and made it look glamorous through the crystallisation process," she says. See them at the Beau Sauvage exhib­ition at the Liberty department store.

Her Kelp Construct lamp, with a shade made using a process that turns kelp into a stiff yet translucent material, will be displayed at Lighten Up, a show mounted by (Re)design at 100% Design in Earl's Court.www.julialohmann.co.uk

Peter Marigold

London-born Marigold studied fine art and sculpture at Central Saint Martins and graduated from the RCA's Design Products course in 2006. Subsequent work on set construction and theatrical props also informs his approach to design. "I bounce ideas off the materials," he says. "Strange things start to happen when you interact with materials and forms so my designs are very much experience-driven."

Marigold will show three pieces at Beau Sauvage. His Thin Slice cabinet is built of thin sections of wood laid out in the sequence in which they were cut to reveal the tree's growth pattern. "My interest is in making certain phenomena become apparent by re-arranging the world around us," he says. This "altered geometry" is also employed in Yield, a large panelled screen wrought from a bay tree.

Marigold shares Okay's studio and will show pieces at Aram Gallery. New work includes Tan, a series of mirrors cradled by hanging cords that encircle the glass and form perfect tangents to their nails. "The world has complex, yet simple, underlying mathematical principles which I try to make evident." Meanwhile the waste timber that's usually cut from the exterior of circular tables is re-positioned in the centre of his three End tables in an inversion of the usual design approach.www.petermarigold.com

London Design Festival, until September 23