Cheap knockouts

[GRIM]

I frequently use electricians knockouts to make holes for inlets etc, not sure about the quality of these ones, but they are real cheap for those who have the access to these stores , the step drills are also excellent for pulsejet construction ,

http://www.harborfreight.com/cpi/ctaf/d ... mber=91201

http://search.harborfreight.com/cpisear ... tep+drills