From our phones to our fingernails, we're a nation obsessed with customisation.

We want everything and we want to make it our own. The cynical might say it's simply a reaction to the ubiquity of, well, pretty much anything these days. Others may suggest that it's simply nice to be in possession of something that entirely reflects you and your tastes.

Either way, customisation and bespoke services are on the increase among fashion houses this season, with two major launches for the pickiest aesthetes at ultra-luxury labels Bottega Veneta and Louis Vuitton. The first takes inspiration from the brand's elegantly understated tagline "when your own initials are enough", and gives customers the chance to decorate its distinctive woven leather holdalls and handbags with chunky, Scrabble-esque letters in a range of eight colours.

"It allows us to take the customer-centred philosophy of Bottega Veneta one step further," explains creative director Tomas Maier, whose aesthetic at the label is very much about individuality and personal taste. "The process is fun."

Likewise with Louis Vuitton's new Haute Maroquinerie service, which now operates from a private salon in the London Bond Street store. Customers are involved in every stage of designing their handbags – choosing from five styles (three of which are already iconic among the Vuitton back catalogue) and then deciding on colours, lining and hardware. When you've finished playing with supple and smooth fabric and leather swatches, or picking from the coffret of zips and clasps, the entire package is sent to the house's workshops in Asnieres to be made up by Vuitton's own in-house artisans.

But it doesn't end with bags. Of course, bespoke has its roots in clothing, from the ateliers of Paris to London's Savile Row – but the trend for one-offs now extends to stationery (at Smythson, initials can be added for a small fee), life admin (Anya Hindmarch's bespoke services will create document wallets and files decorated with names and other details) and even your underwear drawer. Loredana Tarsia's firm Lingerie d'Elia is an Italy-based company which has created made-to-measure silk and lace pieces for the likes of Lauren Bacall and Princess Diana from its boutique on Rome's Spanish Steps.

"In a world where everything is available, a truly handmade and bespoke product is very hard to find," she says. "A bespoke service places customers at the centre – their desires are handmade for them."

"'Bespoke' is used pretty loosely in the world of luxury at the moment," says Penny Martin, editor of The Gentlewoman. "It can refer to services that will guarantee a better fit, customisation to ensure your expensive garment or accessory is somehow distinct from all the others in the room, or some expensive handwork so tricky to reproduce that nobody could turn up with a fake – perish the thought.

"What unites all of those options is that they require the purchase of a fairly simple, classic item in the first place: not an outlandish one-off," Martin continues. "So what the rise of bespoke tells us is that it's aimed at a fairly conservative consumer who is prepared to decorate a staple item that will last them several seasons rather than invest in radical design."

Certainly this is the case with Prada's popular Made To Order service on handbags and leather goods, which means customers can choose the colour and finishing details of their purchases – the label's Galleria tote is a popular choice to reinvent in any shade, made from a range of leather, skins and silks, and is a suitably timeless piece of arm candy.

It re-enforces the point – and it's a significant shift in the market – that those clients who may once have traded in their It-bags with the arrival of the each new season's range are now looking for something that stands the test of time; that they won't tire of or see thousands of being carried down the street in front of them.

If the It-bag was a status symbol, then the perfect-fit bag is even more so, as it implies one has opted out – or is above – the vagaries of relentless trend cycles.

"Customers are looking for exclusivity, quality, creativity and timelessness," says Erich Hager, European Retail Manager at Goyard. The French house has been creating made-to-measure trunks and luggage sets since 1853, and is able to cope with even the most unusual requests, perfectly calibrating its hallmark tessellating prints to each order, be it for a tea-chest, a case for a folding bike or even a jet-set canine armoire.

"At first, we have an interview to understand the expectations of the customer," continues Hager. "Then, from personal requirements given to satisfy a need or eccentricity, we realise sketches with measurements and then a watercolour. It is a real exchange because a special order is a unique item marked with the personality of the customer."

Personalised luggage first came about organically, in an age when a travelling bag was much of a muchness. The seasonal migrations and grand tours of the upper classes necessitated the marking of luggage with initials and, for the showy, coats of arms, all carefully stencilled onto pigskin and leather-bound trunks placed on steamers and locomotives. Through the ages, famous faces such as Audrey Hepburn, Grace Kelly, Joan Collins and Liza Minelli have all trundled their very own, embossed baggage through the arrivals hall. While you might not have the budget to stretch to luxury luggage – and you might not spot a Goyard sailing round the luggage carousel after your Ryanair flight, either – customisation is becoming big news on the high street too: initials, it seems, are one trend that everyone can buy into, whether Varsity-style on Whistles's autumn baseball jacket (the letters are applied free of charge, subject to availability) or stencilled onto a trusty retro bag.

"We have seen a steady rise in the proportion of bags that customers would like embossed," says Julie Deane, founder of the Cambridge Satchel Company, which offers a customisaton service on its nostalgic leather schoolbags.

"The most popular request is for initials, but we've had some more elaborate ones – including one for a marriage proposal! Receiving something that has been tailored especially for you makes it feel that little bit more special."