DIY (Do-It-Yourself) Audio Loops are easy to assemble.
A carrying case if the system is to be portable.
The amplifier should be capable of continuous operation at full power output without overheating. In general, amplifiers designed for public address (PA) meet this requirement.
These pages will give components for a loop size of 100 feet. Larger areas require bigger, more powerful amplifiers. These installations should be installed and specified by a professional.