[BrianG]

Be careful when you go to pick up a switch. There are several SPST switches at Radioshack. The lower current ones work fine, but are more easily actuated by bumps and hard landings. The high current verions (5A+) take more force to get them to switch so they are less likely to turn off by themselves.

BTW: You can use SPDT, DPST, and DPDT switches too; just don't use the extra terminals. I usually cut them as close to the case as possible and heatshrink the whole thing.