If you own a circular saw, you can make accurate, safe cuts on plywood and other sheet goods with an inexpensive saw guide that's easy to make yourself.
Circular Saw Tips and Techniques (DIY)
Make a Simple Circular Saw Cutting Guide
Build Your Own Track Saw for Straight, Accurate Cuts
Premium Home Improvement: This saw guide turns your circular saw into a precision edge-guided tool Woodworking Tools: Universal sled holds guide rail
Kreg KMA2685 Rip-Cut Circular Saw Guide , Blue
American Express
Rockler Taper Straight Line Jig
Circular Saw Uses: How to Use and Cut Wood With a Circular Saw
How to Make Rip Cuts with a Circular Saw - Pro Tool Reviews
SawGuide™ - Milescraft
Circular Saw Guide, Track Saw, Saw Track, DIY Saw Track, Cross Cut Track Saw, Track Saw Guide