A Pin Drill or Pin Vice is a micro drill set used for modeling hobbyists for several different things. Most commonly they are used to make small diameter holes for decoration or to insert a rod into for stability of a model. A pin drill is one of the most common tools in a modelers toolbox and it is not uncommon to have more then one. Another use is for holding models while you are painting them. By inserting a wire into the bottom of the model and placing it in the pin drill you are able to manipulate the model without having to touch the areas you have already painted. The basic design of the pin drill is pretty much the same in concept tho there are several different types.
They will all have a cylinder with an ending with a collet nut that screws on over a collet causing it to tighten and close over what is inserted in the end. Normally one end has a collet nut, and the other ends in some type of swivel. Some being small while others are a large ball. Different modelers have different opinions on what they like. A typical Pin Drill will only have one collet nut, tho there are types that have one on each end. Inside the pin vice is normally 2 collets (each with 2 opening sizes). Each collet can hold a variety of sized drill bits, ranging from 1/8th of an inch to hair thin.
There are some types that have an assisted function. Basically its a part that slides up and down causing the drill to spin. It can speed things up and be a bit easier.
Some things that you have to be careful about. The drill bits are sharp and very small. Do you put to much pressure on them or they can snap. I would recommend not holding a model you are drilling in your hand so in case it breaks it will not stab you.
Overall this is one item that I could not do without. I have had my pin drill for over a decade and have been meaning to pick up a couple more for painting models. Even as a novice this is an item that you should learn with, tho not difficult it can make you a better hobbyist and modeler.