I found myself needing a couple of sawhorses, and I have a bunch of pallets... I went online and found a guide, but it was (imho) somewhat of hard to follow with no pics. So I used the basic idea and built my own. Enjoy.
Step 1: Tools and Materials
This is my list of tools and materials it is by no means absolute but it is a start.
A crowbar, wonder bar or nail puller.
A claw hammer.
A tape measure.
A speed square.
A a skill saw.
A drill bit, for pilot holes, the same size as your screws shaft.
A screw bit that fits your screws.
2 ½ or 3" and 1 ½ screws. Coated, galvanized, or not, your call.
A stack or so of pallets.
If you have better, different, or want to use store bought # 1 pine that's cool. I used pallets because they are free for me, and cheap for anybody. If you buy pallets be somewhat picky. Pallets get used hard, often the wood they are made out of is not of decent quality for anything but pallets. Pick good pallets.