Here I'm setting up the wing to cut the groove on the bottom side for the included tubular graphite spar. I use a Dremel with base and 3/16" router bit. You just lay out the location as shown on the plans, tape down a straightedge, and guide the tool along. Easy and neat. Much better than cutting a groove with and Exacto knife. Another shot shows the finished job. I've used every known adhesive on foamies and what I'm happy with now is to tack glue, if needed, with foam safe ca and then glue with Formula 56 canopy glue. I holds like mad and unlike ca it will flex without cracking.