These individually-addressable RGB LED strips are great for all sorts of uses: custom desk lighting, music or data visualisation (an LED thermometer?), or art installations. They come in three different pixel-spacings.
Addressable LEDs, like these NeoPixel-compatible ones, let you individually set each LED in the chain to a specific RGB colour. You can use a Raspberry Pi, Arduino, micro:bit, or other microcontroller to code them, and there are tonnes of different Python, MicroPython (or CircuitPython), Arduino, and more code libraries available.
These LED strips come in three different spacings—30 , 60, or 144 pixels per metre—and in metre lengths, so if you order a quantity of 1 then you'll get 1 metre, a quantity of 2 is 2 metres, and so on...
Be aware that if you order a 1 metre length of either the 30 or 60 pixel per metre strips then you may or may not get a connector on one or other of the ends. The 144 pixels per metre strips come ready-made in 1 metre lengths, so you'll get a connector on both ends of the strip with them.
The strips come with a flexible silicone waterproof sleeve, but this can be easily removed, if you like. If your metre length doesn't have a connector on one or other end, then you can use a little blob of hot glue to seal the flexible sleeve.