To craft tools in Tinkers'Construct, you first need to collect the right parts. The different parts of a tool can be collected from the Tool Parts Shelf in the Part Builder.
Once you have your parts, you need to build a Tool Station. This will allow you to combine the parts of your tools into one unit. To build a Tool Station, first use the Construction Plate to create a square area on the ground. Then use the Build Pillar Tool to place two Metal Posts inside the square area. Finally, use the Forge and Smeltery to craft your tools.