This is a very easy project but, as easy as what it is, it can go wrong if you do not use the right glue. Make sure you use a multi-purpose type of glue like Tombow Mono liquid glue. Please check the packaging, it must stipulate that it sticks onto plastic and that it dries clear.
Start to coil the plastic tube into a spiral pattern. Add the glue between the tubes and hold it together, this will help with the bonding. I know the process is slow but be patient, the end result is so rewarding. Carry on doing this until you are satisfied with the size of your coaster. Glue the end part neatly to the side. Make as many as you want, this will protect your furniture from water stains or keep your glasses in place on the dinner table.