The Adafruit GEMMA has three available digital I/O pins, but thanks to the technique of Charlieplexing you can drive up to six LEDs with those pins, one at a time. In general, charlieplexing allows n tri-state pins to control n^2-n LEDs. My example Arduino sketch in github/charlieplex generates 8-bit PWM for each of the six LEDs, although it does require the full CPU to do it. Here is a short video of it in action, showing the smooth fades on and off.
My sewable sequins are made from 0805 surface mount LEDs and small metal beads from a local shop. Becky Stern of Adafruit has a great tutorial on making LED sequins — I used smaller LEDs than Becky, so I had a harder time putting them together and had to build a small jig with a piece of wire to support the bead while soldering it under a microscope. If you don’t need the small size, Adafruit’s premade LED sequins are a much easier way to add them to your project.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.