Following on the subject of gun and gun culture I have looked into the issue both from the angle of homicide and suicide and have been refering to a report called Guns & Suicide - The Hidden Toll
For more information on the issue refer to guns as this post deals with the practical issue of making a mold.
There are many way in which you can make a mould and the material you use depends on many things. Some moulds like silicone ones are durable and ideal for objects you want to cast over and over again, however silicone is relatively expensive in comparison another casting material - plaster of paris. I decided to make a two part mould from silicone for a variety of reasons. I wanted a mould that would last a long time, I intend to make a lot and because silicone is so flexible it is easier to work as it can flex round the object making it much easier to remove from the mould.
To begin with, you need to choose your object, in my case a BB Gun (toy gun that shoots pellets). In order to make a two part mould you need to build a wall in order to contain all the materials. In this case I used lego on a Lego baseboard. I think found what is referred to as the horizontal line of the gun. The plan is to make one side of the mould first and then the other. So with the brick wall build the area was filled with clay and the gun was placed on a bed of clay. The idea is to cast the top side first. The gun needed to be prepared to fill in any holes, else when the silicone is poured there is a danger it will run into the inside of the gun and that would be somewhat disastrous. So with the gun prepped and sunk into the clay with the top side exposed I began to mix up the silicone. The silicone comes in two parts and I bought mine from the very helpful . As I said, to make a mould you need to mix two materials, the thick gloopy silicone and the chemical that will make it set. The set time is dependent on what chemical you use. There is one that cures in 10 hours and another that takes 24 hours. I chose the 10 hour one that is pink in colour. The longer the cure time chemical you use the longer the mould will last as it will deteriorate much slower ( we are talking years here not weeks or months).