My first bits of rope I purchased from one of the large chains of DIY shops. Some of it was washing line and some was for replacing the rope in sash windows, and I also tried a bright orange line for marking out.
I was so pleased with my first monkeys fist, but looking at it a few months down the road...........eeek what a horror!!! Now though I have tied a fist around a small ball-bearing and it does look good. You may want to tie one around a cork ball, so that if you drop your keys in the water they will not sink??
I purchased lots of coloured para cord off eBay and produced a mass of colourful knots and keyrings. I ran out of friends to give them to before I ran out of rope.
I then started to scale up my operations and decided to make a fender. My first one was small, actually using the window sash cord. I now have a few fenders hanging inside and outside of the house. To this day not a single vessel has crashed into the house - so they work!!!
I then bought myself a length of fairly thick rope and produced a rather nice round mat from it.
Different materials produce different results, some horrors some fantastic, but the one constant that I have is that I enjoy it!!!