I built my outer panels with my Center spars in a roll over jig, using the AS504x airfoil templates and a lazer level makes it easy and accurate and doing the foam and glasswork is easier also because the work can be turned over to the best position to do it in. I also hot wire cut my foam cores from extruded styrofoam which made shaping the cores a snap to do and accurate also. I hate urethane foam and won't get into a debate about the pros and cons, I just know what I prefer. I found this method to be far superior to the way the plans suggest to build the plane as I built my KR1 religiously to the plans and have had plenty of time to think about how I wasn't going to do it the next time around