Sentence:  He also bought a huge square of pegboard for hanging up his tools , and lumber for his workbench , sandpaper and glue and assorted nails , levels and <WSD>T</WSD> squares and plumb lines and several gadgets that he had no idea how to use or what they were for . 
Meaning of the word marked with <WSD> tags:  a square used by draftsmen to draw parallel lines