The next step was to lay out the fin shape on the plywood. I cut out a template from cardstock to assure better uniformity. It took several tries to get the fin root just the right depth to attach to the motor mount tube, both CRs and the body tube. The slots in the "fin can" were cut with an Exacto knife to slightly larger than the stock thickness. Then I broke out my new Ryobi scroll saw and presto voila!!