The choice of screwdriver design relies on the fabricator's choice. Comfort is key, #0, #1, #2 Robertson, #2, #1 Philips, Large, medium, small slotted are needed. Metric Allen keys are also needed, 2mm, 4mm, 8mm. 3/16 and 1/8 are nice to have as they are project specific but will not be used often.
There are 3 parts of screwdriver: a handle, shaft, and tip (or blade). The tip of a screwdriver may be strengthened with a denser metal to resist wear or magnetized. Handles can be made from many materials. Larger screwdrivers offer greater torque when turning screws, smaller ones are useful in tight places.
Screwdrivers can come in 4 basic forms: Manual, Interchangeable, Ratchet, and Power Drivers. Screwdrivers are classified by their tips which uniquely correspond to screw heads: 'Slot' (Flat), 'Phillips' (Cross), 'Hex' (or Allen), and 'Robertson' (Square).
Types of Screwdrivers
The most common and often packaged with all the standard blades together. The most sturdy but take up the most space. Can be magnetized.
A manual driver, these usually have hollow handles where a collection of changeable tips can be placed and removed when required. These can be magnetized as well. Due to the storage capacity of the handle these screwdrivers can be uncomfortable. Some interchangeable sets store the changeable tips separately, increasing comfort of the grip.
Able to be used with a small range of motion. The 'ratchet' lock mechanism drives the screw in a clock-wise turn, when unlocked it removes the screw in a counter-clockwise turn. These are best used when screws are located in tight places, where it can be hard to rotate the screw 360 degrees to tighten or loosen it. These can also typically have hollow handles for screw bits.
Can be battery, cord, cordless, or pneumatic screwdrivers with interchangeable blades and often used when manipulating a screw through a dense material.
Types of Blades/Tips
Slot "Flat" Blade
Hex "Allen" Blade
Robertson "Square" Blade
From Left to Right: Torx, Slot, Pozidriv, Phillips, and Hex