If you clamp them to a carpenters square you not only get a true 90 degree angle you leave your hands free to drill the screw into place.
DIY sawhorse from pallet wood
The Kreg a great invention. It works better in hard woods than in softer woods like pine. It's one of those thats hard to beat at its specialty.
Bench made from recycled wood and concrete
sanding and priming MDF furniture for a new paint job