Under the box lid of a Sears Craftsman 45° miter cut-n-clamp set, which was produced in the 1960s.
- Measure the width of the picture. (X in inches)
- Measure the width of the molding. (Y in inches)
- 3 Add twice the molding width (2Y) to the picture size (X) then subtract 0.5.
- This will give you the length to cut your molding. (L in inches)
Then you can do the same thing for the opposite dimension if your picture isn’t a square.