Once your map starts getting big, walking everywhere gets old fast. Portals fix that. They let you jump straight from one spot to another, and honestly they are the thing that made me actually enjoy exploring. Here is how to build one.
What you need
One portal is not enough on its own, you always build them in pairs, so double these numbers. For a single portal you need:
Fine wood
20- Surtling core
2 - Greydwarf eye
10
You also need your 
Hammer out and a 
Workbench nearby to build, same as anything else.
Where to find the materials
Fine wood comes from birch and oak, and you will need a bronze axe for those. If that part is new to you, I wrote up how to get Fine wood separately. 
Greydwarf eye drops from greydwarves, those little bark creatures that swarm you in the Black Forest at night, so you will have piles of these in no time. 
Surtling core is the tricky one: look for Burial Chambers in the Black Forest, the stone dungeon entrances, and you will find cores sitting in glowing green stacks inside.
The one rule to remember
Both ends of a portal need the exact same tag, the little name you type in. Match the names and they link up straight away, two way. The big catch: you cannot carry metals through a portal. Ore, ingots, all of it gets blocked, so you still have to sail your copper and tin home the slow way. Everything else travels fine.
Set a portal up at your main base pointed at wherever you are exploring, and you will wonder how you managed without it. Happy building!
