Source: Windows Central / Zackery Cuevas
Crafting a portal can be done fairly early in your travels, but it requires a few key materials. One of those ingredients is Fine Wood. Finding a piece of Fine Wood will unlock the recipe for the Portal, but to find Fine Wood, you ll have to chop down the Birch or Oak trees found in the Meadows, Black Forest, or Plains biomes.
Both trees require a Bronze Axe to chop down, so you ll have to have discover Bronze first. Fine Wood can also be found in the shipwrecks found on the coast of the Black Forest, or if you re feeling dangerous, you can also tempt a Troll to knock over the necessary trees, but doing so is dangerous.