Place your carpet face down on your work surface. Check straightness of the remnant edge with the measuring tape and marker, marking on the back side of the rug any areas that need to be trimmed with scissors. Cut any protruding edges straight or to the shape you want your rug.
Make a 1/4-inch wide border of white glue on the edge of the rug backing, all the way around the outside edge. Spread the border smooth with your craft stick. Use enough glue that the spread border is still white rather than clear. You can use latex carpet glue if available. The consistency is quite similar to all-purpose white glue.
Leave rug face down on the work surface to dry. This can take from 24 to 48 hours. Press down with a clean craft stick or your thumbnail to determine whether glue is completely dry; this border dries on the outside before the inside is fully dry. Turn the rug over and lay it in place only after the glue is completely dry.
Place rug face down on your work surface. Check with yardstick and marker and trim with scissors any irregularities in the edge of your rug.
Measure the complete length of your rug's border, all four sides added together. Allow 2 to 4 inches more instant binding tape than the full measured length. This will allow for slight irregularities in assembly and let you join the ends of the instant binding tape invisibly.
Turn your rug face up on the work surface. Beginning in the middle of a side, slide peeled instant binder tape under the rug until only the rolled, serged or rope edging shows against the rug. Using your glue gun, fasten the tape to the underside edge of the rug. Apply more glue in the groove between the rug fabric and the binder tape edging. Using your hand on the rug and the wood block pressed against the binder tape edging, press hard to snug the edging right against the rug edge. Continue around the rug edge until you reach the start of the binder tape.
Trim the end of the binder tape so that you can join starting and finishing ends together. Apply glue between the ends and hold together until the glue has cooled enough to hold, usually 10 to 15 seconds. You began applying tape in the middle of a side as that it is much easier to make the joint invisible than piecing it together at a corner.
Turn your rug face down on the work surface to finish gluing the tape. Apply glue to the border on the underside of the rug and press it down with the wood block to make sure it adheres well. At the corners, cut notches in the tape border, either mitering the corners or overlapping tape edges to square the corners.