Set it out
Craft the kit on the Pack tray and place it on level ground. It works like every bench, see Crafting at benches.
What it makes
The bare workbench makes the kits for the Smelter, sawmill table, sword bench, bow table, alchemist's table and Recycler, and the kits for its own add-ons.
Add-ons
Set a copper rail onto it and it also makes the Forge, camp stove and powder bench. An iron frame after that opens the gun table. Make the kit, set it on by hand, and the next benches appear on its list.