A blocking board is a lightweight, pinable board with a fabric covering that has been printed with a grid of squares. The grid is used as a guide for squaring the canvas during the blocking process.
Blocking boards can be purchased through needlepoint, sewing and knitting suppliers and come in severale different sizes and styles.
June Taylor makes a Cushioned Quilter's Square 'n Blocker board that features a handy rotary cutting mat on the opposite side.
My personal favorite is the Webs Blocking Board (shown in the photo) which is available in many needlework shops. The larger size makes it perfect for blocking large projects such as needlepoint rugs or wall hangings.
While a blocking board won't fit into your workbasket, it is an essential tool for straightening warped, finished needlepoint canvas.