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.
Rubber 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.
If using the Cutter on Cables (Insulated or not) it will use or give rubber to un-insulate/insulate wire.