It is important to have a set of hand tools, and below are the recommended tools for pursuing projects, in addition to other power tools.

Soft metals such as aluminum can be easily threaded yourself with a die and tap. A die and die wrench are used to create threads on an outer surface, such as a rod.

A tap tool is used to create a thread in a drilled hole in metal. While it is much easier to drill and tap soft metals use of the proper cutting oil will permit you to drill and tap steel.
A good guide for this is Constructing Robot Bases by Gordon McComb.

Common pliers are important tools for constructing and deconstructing machines. They can come in handy as bending tools if a vice is not available.

Needle nose pliers are important for making finer connections and for holding with precision or getting into tight spots. It is recommended that you have a host of these needle nose pliers.

Hammers are important for a number of reasons and fantastic for making quick temporary of permanent structures and installations constructed of wood. As you look for hammers be aware of the head smoothness to as some hammers have rough heads and can mar softer woods like pine so a finish hammer may be a better purchase.

Matt knives are valuable for a number of reasons. They can be used with metal rulers for cutting cardboard or paper, plastic or for cutting thin balsa and bass wood.

Utility knife