[header] How to build an airsoft artillery piece [title] Make a base block. [step] Use a good, strong piece of wood about 2 feet (0.6 m) by 2 feet (0.6 m). This will be what everything else is built on. 
[title] Get a 2 by 4 approximately 4-5 feet (1.2-1.5 m) long. [step] Attach this to the top center of the 2 by 2 foot board with the end of the 2 by 4 matching up with the opposite side of the board so now it sticks out.