How to Install an ATtiny Bootloader With Virtual USB
Contributors:
Shawn Hymel
Shawn Hymel 
Resources and Going Further
While this is a lot of information to take in, it shows how to hack the Arduino IDE to load custom board definitions. These steps should work for other ATtiny devices that are supported by the micronucleus project, such as:
You might have to modify the pins_arduino.h file, however, if you plan to use a different ATtiny.
ATtiny84 Pinout
If you need additional support, please check out the following resources.
If you want to go further with the ATtiny, please check out our additional tutorials that showcase the ATtiny:
Firefly Jar Assembly Guide
Make a soft circuit firefly jar with conductive thread, LEDs, and the LilyTwinkle!
Twinkle Zodiac Constellation
Create a quick and easy piece of e-textile art based on a Zodiac sign using a LilyTiny, LilyPad LEDs, battery holder, conductive thread, and coin cell battery.
Qwiic Twist Hookup Guide
Take your volume knob beyond 11 with the Qwiic Twist digital RGB LED encoder via I2C!