Speed Square
$9.50 at amazon prime Swanson Tool S0101 7-inch Speed Square
$20 at amazon prime Swanson Tool S0107 12-Inch Speed Square
$11.50 at amazon prime Swanson Tool T0701 12-Inch Speedlite Square (Structural Foam Plastic Orange)
$15 at amazon prime Stanley STHT46011 12 Inch Dual Color Abs Square
$6.37 at amazon IRWIN Tools Rafter Square, Hi-Vis, 12-Inch (1794467)
youtube Wranglerstar - Speed Square Top 5 PRO Tips