A little stool or a straight-backed chair is a useful addition to any room, and if you make it yourself, the style and colour can easily be suited to your needs. If you're ambitious enough, you could even create a whole dining set, provided you can find a table frame. Nylon or polypropylene ropes (also known as "ski rope") are strong synthetic choices and come in a variety of colours, while the earthy tones of natural fibre rope will foster harmony amongst neutral surroundings. Be sure to use a good wood sealant for the frame--and the seat if you're making it in natural fibre rope--if the furniture is intended for outdoor use.
Tie the rope to a bar on the seat with a simple overhand knot, leaving a tail as long as the bar you are knotting onto. This should be done on one of the short sides if you have a rectangular seat. Run the rope over the top of the opposite bar, under the bar, back to and up over the first bar, holding the tail along the length of the bar so the rope covers it as you work.
Continue winding the rope around the two bars in this way until you fill the entire space, with the rope forming a dense mat in the middle, covering the two bars completely. Make sure you keep the rows tightly lined up against one another.
Loop the rope over the top of the bar on the last row and then under the bar next to it, turning the corner to start weaving across the strands. Run the rope under the strands to the end and push it up through between the bar and the strands on the other side. Loop it over the bar and bring it back up through between the bar and the strands. Run it back across the top of the strands.
Push the rope down between the bar and the strands and loop it up over the bar. Push it back down between the bar and the strands and run it back along the underside. Ensure the strands line up tightly to create a dense covering. Continue doing this until you have completely filled the entire space. You should now have a layer above and a layer below the rope strands running lengthwise from Steps 1 and 2.
Finish your covering by tying the rope to a strand on the underside in three equidistant spaces, or for a more decorative look, tie it diagonally across the bottom in three places, working from one corner to the opposite corner.
Repeat these steps for the back of the chair, if applicable.
Use the rope in one continuous length. Once the lengthwise strands are in place, you could weave the crosswise strands through in an under-and-over manner to create a more woven look. Another way to knot the ends is to leave the starting tail out and tie it to the finishing tail, after tying the finishing tail to the bar.