Tinkers' Construct 3 is the modern progression used from Minecraft 1.16 onward, not a drop-in continuation of every 1.12-era tutorial. The Part Builder handles early tool parts, the Tinker Station assembles basic tools, the Melter introduces metal casting, the Smeltery unlocks bulk melting and alloys, and later progression adds broad tools, advanced modifiers, the Foundry, and Nether resources.
Start with the release generation
Before following a tutorial, identify whether it was written for the modern Tinkers 3 era or an older generation. A guide can be well written and still be wrong for your installed version.
Learn the workstation flow in order
Do not rush to advanced modifiers before you can reliably create parts, assemble a basic tool, repair it, and interpret the statistics shown by the current interface.
Compare materials by role
Choose materials for the task you want the tool to perform. Mining, combat, durability, utility, and modifier plans can lead to different sensible choices.
Add modifiers with a purpose
A modifier is most useful when it solves a specific need. Build around a clear job for the tool rather than adding upgrades only because slots are available.
Use version-matched reference material
Search terms such as Tinkers' Construct Wiki can surface mixed generations of information. Always cross-check the Minecraft version and major mod generation before applying a recipe or mechanic from a reference page.