Builder gel is a type of gel polish with a thick viscosity that is used to create length, thickness or strength on your natural nails or nail enhancements (i.e nails tips). Builder gel can be separated into two categories, builder gel or builder gel in a bottle (BIAB) and hard gel. Builder gel in a bottle is a softer gel, but it creates a much stronger overlay on the nails than traditional gel nail polish so it’s great for helping your natural nails grow. If you’re a nail-biter, it’s also a sound option to protect your nails because it’s too rigid to bite through.