In a large bowl, stir together the nut or seed butter, liquid sweetener, and vanilla until smooth and glossy.
Mix in the rolled oats, shredded coconut, chia seeds, ground flaxseed, and salt. Stir until every oat is coated and the mixture looks sticky, not dusty.
Add the chocolate chips or cacao nibs plus your two or three chosen mix-ins. Fold gently so everything is evenly distributed.
Cover the bowl and refrigerate for 15 to 20 minutes. This firms up the butter and makes rolling far less messy.
Scoop about 1 tablespoon of dough at a time and roll into 1-inch balls. You should get 16 to 20. If the dough is crumbly, add 1 teaspoon of water or milk; if it's too sticky, add a spoonful of oats.
Place the balls on a parchment-lined plate and chill for another 15 minutes to firm up. Eat straight from the fridge.