There's already a handful of colour options for the Nintendo Switch's main controller, the Joy-Con. The standard grey, red & blue launched with the console in March 2017. Then came yellow Joy-Con in June with the release of ARMS, and green (left) & pink (right) Joy-Con with the release of Splatoon 2 in July. However, these colours have previously only been available in preset couplings. This means if you wanted, for example, a red Joy-Con L and a yellow Joy-Con R, you'd have to buy 2 pairs of controllers. Recreating the MasterCard logo in the palm of your hands, has never been so expensive.
But Nintendo have made a step to remedy that. Nintendo are now allowing buyers to purchase Joy-Con for the Nintendo Switch in any combination of colours they please. And that goes for Joy-Con grips too. They also allow you to create your own console bundle, adding things like a game, the Nintendo Switch Pro Controller, or an all essential carry case. At time of writing, this is only possible in the Japanese Nintendo online store. But it may be so long before stock availability gets to a realistic level, customisable Joy-Con may have released in the west, the Antarctic, and another planet or two before you'll actually be able to get your hands on them.
There already exist a number of online outlets where players can design and purchase a custom built DualShock 4 controller. Furthermore, the Xbox Design Lab has an incredibly robust builder for that perfect Xbox One Controller. So Nintendo have quite a bit to catch up on in allowing their players to fight fearsome bosses with skittles-coloured controllers.