Trap machines shoot targets, called "clay pigeons" into the air for marksmen to "kill." Practice always increases skill, but practicing trap shooting can get expensive if using store-bought clay pigeons. Making a DIY clay pigeon is not complicated. As long as the mould used maintains the basic regulation saucerlike shape and is no larger than 4.33 inches in diameter, the practice will be of benefit.
In a double boiler, heat and mix roofing tar and calcium carbonate until it is evenly blended. Maintain a ration of 40 per cent calcium carbonate to tar. One standard-size pigeon will require 198gr. of the mix; adjust amounts accordingly to make enough for the total amount of pigeons to be cast. A good reference amount to remember is that 1 gallon of mix will yield about 24 pigeons.
Ladle the mix into the rubber pigeon mould. Make sure the mould is filled to the brim and is seated firmly on a surface that will prevent it from tipping while being filled. Allow the mix to cool for several hours.
Peel the rubber mould off the clay pigeon to release it.
Paint the clay pigeon in a colour that will give it the best visibility in the field. Use dark colours for daylight shooting and fluorescents for night shooting or shooting near heavy foliage.
Dust the inside of the rubber mould with a light coating of calcium carbonate to prevent the mould from sticking to the pigeon as it cools.
Hot roofing tar releases carcinogenic fumes -- always work in a well-ventilated place and wear a breathing mask designed to prevent inhalation of the fumes.