I have heard of a method that cuts a core from root to tip...one core in front of the tube, one behind. It requires burning the wires into the core, then sheeting, then using these wires and templates to burn each core out of the panel. I have not yet tried this method, but I have seen the results and it looks good. This method also prevents the sheeting from having to span open (unsupported) bays in the foam core.

-mark