Cut four boards of scrap lumber or new lumber. Each board should be 1-by-2 in dimension; the length and width you cut your boards will determine the size of the rugs you can weave. For a standard size, cut two 4-foot lengths and two 3-foot lengths.
Position your cut lumber on the floor or a large work area in a rectangle. Put the two 4-foot lengths parallel to one another and position the 3-foot lengths between them, at the top and the bottom.
Nail the boards together at the corners. Two to four nails at each corner should give them a sturdy join. Nail the pieces so that the 3-foot boards slightly overlap the 4-foot boards at the top and bottom.
Measure across the top of your loom, every 1 inch or so. Mark these points with a pencil. Repeat this step across the bottom of the loom, making sure that your bottom markings line up with the top markings.
Use a drill to insert a screw into the wood at every pencil mark across the top and bottom. Let the screw heads stick out of the wood by 1/4 inch or so. These screws will hold your warp thread for your rug weaving loom.