Building is a separate mode. When you press B, your crosshair turns square, the hotbar switches to the block palette and you can no longer chop trees — you only place and break blocks. Press B again to leave.
Place a Block, Break a Block
In build mode, right click places and left click breaks. Both take a single click; holding the button does nothing — otherwise you'd leave a trail of blocks behind you every time you turned. A block you break comes back as material, so trial and error costs you nothing.
Facing and Shape
R turns the block you're about to place a quarter turn, G changes its shape: full block, slab, stair. On a cube R has no visible effect, so the new facing is written on screen; on a stair the ghost model already shows which way it will face.
Stations
The workbench is made by hand; it makes the other stations, your first tools, furniture and your first machines (Breaker, Collector, Charcoal Burner, Solar Panel). The Chest, Vault and Trading Port are made at the workbench too, but they have to be researched at the Monument first. The furnace casts ingots (copper, tin, gold, iron, bronze) and makes charcoal, bricks and glass. The loom gives rope and cloth. The anvil makes every axe, pickaxe and sword from copper up, plus gears and circuits — it needs ingots. The kitchen cooks food. The Assembler unlocks with the Assembly research and makes advanced machines — it needs gears. The Enchanter makes dungeon keys.
Where to Craft
You can make the simplest member of each family straight from the Q catalog: queue it wherever you are (up to 5 jobs), it finishes while you walk and drops into your bag. Upgrades need their own station — for Collector II, Breaker II and above you have to stand at the Assembler, and for copper-and-up tools at the anvil.
Blocks you place follow the same rules as the ground: you can stand on them and wall-run along their edges. If you're snagging on an invisible wall, F3+B turns on the collision boxes and shows you what you're hitting.