Try this strategy for making clean, consistent, and repeatable angled cuts. On one panel with the appearance side down, mark a line precisely where you want your final cut. Using a straightedge and a circular saw or jigsaw with a plywood-cutting blade, cut to within 1⁄8" of the line on the waste side, as shown. Then reposition your straightedge, and use a router with a top-bearing straight bit to trim the panel to your marked line. This piece now becomes the template for the remaining parts. ...