the.com/miter box

A plastic jig that lets you cut 45 degrees without lying to yourself about it.

means A guide tool with slots at fixed angles (usually 45° and 90°) that holds a saw steady so you can cut clean, precise angles in wood or molding.

from From 'miter' (also spelled 'mitre'), the carpentry term for a joint where two pieces meet at an angle — itself borrowed from the French 'mitre,' meaning a bishop's pointed headdress, likely because the peaked shape of a folded miter joint resembled one. The 'box' part is plain and literal: early versions were literally open-topped boxes with slots cut into the sides to guide a handsaw at the correct angle.

basic version
Just slots cut in a U-shaped channel
upgrade
Miter saw is this box with a motor and ambition
common angles
Usually slotted for 45 and 90 only
humbling fact
Still possible to cut the wrong angle confidently
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