Mason's Line Corner Block
An L-shaped string-line block that hooks over the corner of a brick course, board, fence rail or raised-bed frame. A 1.6 mm loading kerf holds the line flush with the face, and a tapered jam slot on the back locks the wrapped line without a knot, so line tension pulls the block tight against the corner. Print two for a run. The block is 55 x 50 x 30 mm, the face leg is 45 mm long, and the hook leg reaches 40 mm around the end. It takes standard #18 braided mason's line up to about 1.5 mm.
tool mason-line string-line layout