Factory to craft Belts, Splitters and Underground Belts.
Expand your production by stages by applying each blueprint over what you built in previous stage, from yellow to blue, and ready to add beacons and modules.
Before applying the 4th blueprint over previous built, use upgrade planner or manually build over to switch Wooden Boxes into Buffer Chests (green), to recycle older belts from deconstruction by bots as ingredients to produce higher tier ones (you also can upgrade belts from yellow to blue when you get enough).