Thread one end of a piece of scrap knit fabric through the end of the darning needle (Image 1). Line up the floor mats end to end (the ends you want to connect), make sure they are even. Push the needle through one end of the floor mat (Image 2). Bring the needle back through the other floor mat, connecting the two (Image 3). A knot in the scrap (Image 4).
Repeat the process along the side of the mat, connecting the two together (Image 1). Repeat for additional mats until desired length. Cut off the excess ends of the knit ties, if you want to hang a little from both sides (Image 2). Enjoy your finished rug (Image 3).