Circular Saw Crosscut Guide. by setting this up with an open bottom of box, it could be used to used on "planning to thickness" of even large odd shape pieces. mount these to base with wedges to not screw into your finished work.
Make on-the-mark cuts with your circular saw Fast to set up and highly accurate, this cutoff jig was designed for boards. But you can increase the width for larger workpieces, or angle the fence and enlarge the jig to make cuts.