Sticky resin can be extracted or smelted to create rubber. When you smelt the sticky resin in a furnace it yields one rubber but if you extract it in a extractor it produces three rubber. Rubbertree wood can also be extracted but it only makes one rubber per wood.
As a Crafting IngredientEditRubber is used to insulate cables of all kinds ( excluding glass fibre cables ) the picture to the right shows how to make an insulated copper cable. Using the lower recipe you can make rubber boots which eliminate fall damage up to 10 blocks.