Most improvised explosives are comprised of chemical constituents easily found in any home or local community, even in large quantities. Improvised explosives can be as effective as manufactured explosives in many applications. Terrorists employ these in all sizes of devices. Indicators include

• Commercial coffee grinders are very effective for the process of grinding.
• Grist mills for the crushing of barley or wheat are also effective. A ton of material can be processed through one this size in about two hours. Consider how terrorists might access such a machine.
• Odd job mixers or even a concrete mixer would be suitable for the mixing of the ammonium nitrate and the liquid fuel.
• Improvised incendiaries can be made by mixing strongly reactive chemicals such as strong oxidizers and fuels.

An IED generally consist of five components—power source, initiator, explosive, switch, and fragmentation. These components can be easily remembered by the acronym PIESF.

• Power sources—The majority of IEDs contain an electric initiator and, as such, require an electric power source. Batteries (a common power source) are manufactured in numerous shapes and sizes.
• Initiators—Blasting caps or flame-producing components like fuse igniters for a length of time fuse. Improvised initiators causing low explosives or highly sensitive high explosives to detonate can easily be made. Examples of improvised initiators include a modified flash bulb, a percussion primer, or even improvised hobby fuses that impart flame much as time fuse, only at an uncontrolled burn rate.
• Explosives—When an explosive is incorporated into a device, it is not necessarily in contact with all other IED components. Often, these components will survive in some form after a device detonates. Recognize there is always evidentiary debris at a post-blast incident.
• Switches—Incorporated into a device as either an arming switch or a fuse. They can be simple or complex in nature. More than one switch can be used to create redundancy in the system. Many IED will incorporate both an arming switch and a fusing switch. Switches are almost unlimited in design and constructed so any approach or action by its intended target or a first responder will result in detonation. Switches specifically for IED can take on any form and can appear quite innocent looking—completely fitting into the environment.
• Fragmentation and shrapnel—Part of the IED, wherein materials are added to the device for inflicting maximum casualties. Examples include ball bearings, nails, BBs, etc.