ATTINY85 with RGB LED
The newest blinkstick uses an addressable led, while the Adafruit kit appears to use a regular 4 pin RGB led. These are easier to get.

The digispark and the blinkstick are almost identical, but they use different pins for the USB connection. So to use the firmware for the blinkstick on the digispark, you need to change the pin numbers in usbconfig.h

#define USB_CFG_DMINUS_BIT      3
#define USB_CFG_DPLUS_BIT       2


PS. the pin numbers in usbconfig.h don't seem to match the schematic, so I'm not sure what's going on