Pick two or more rug samples of the same size and shape. Choose the ones that are bound on all edges and do not have holes punched in them. Select two samples to make a small door mat. Use three or four rug samples to create a larger mat.
Flip the rug samples over to work from the back side. Turn them in various directions until the edges align tightly enough. Rug samples are seldom perfectly square.
Tear a piece of duct tape about 6 inches long. Work from the center vertical "seam" (or either one of the seams in a three-sample mat) and place the duct tape horizontally across the middle of the seam.
Add a 6-inch long piece of duct tape a few inches above and below the middle to secure the vertical seam. Connect any horizontal seams for a large mat in a similar manner, placing the pieces of tape vertically.
Flip the mat over to the front side to check its appearance. Flip it over again to the back side to make changes, tighten seams or re-tape any areas as necessary. Tape all the seams vertically to secure them completely when you are satisfied with the doormat's look. Flip your mat over once again to the front and place it at your door.