Using a power drill and paddle attachment mechanizes the job of stirring paint, but it can cause splatters. One way to solve the problem is to use a paper plate. Punch a hole in the center of the plate and push the end of the paddle attachment through the hole before chucking it into your drill. Then hold the plate down over the open can while stirring.
A fastener in sheet metal should not be any closer than four to six diameters from the next one. For example, if you are using a 1/8-in. Pop Rivet, the nearest another rivet should be is between 1/2 to 3/4 in. By using this rule, you will reduce the chances of damaging a part, as well as make optimum use of your fasteners.