Place sugar, lemon peel and blueberries in an electric coffee grinder or small blender and blend or pulse til fruit is incorporated. You may have to stir the mixture halfway through -- the whole process should take only about 10 seconds.
Dump sugar mixture into bowl, then add avocado oil and blueberry flavor oil. With your fingers, rub the oil into the sugar until you achieve a consistency you like (if it's too dry, just add a tiny bit more oil).
Package the lip scrub in a small jar or several small jars if you're sharing. Keep scrub in a covered container in the fridge and discard if it begins to smell odd or to show presence of mold (unlikely, but I gotta say it).
Notes
Keep scrub in a covered container in the fridge and discard if it begins to smell odd or to show presence of mold (unlikely, but I gotta say it).