Wow! 150' of 3/4" line. That's some big stuff. The links that Willike gave show how to tie a Monkey Fist in small stuff, on your fingers. For 3/4" line you will need something a little bigger, and it wouldn't hurt to have a friend help out.
You can probably tie a Monkey Fist around a large beach ball, and cover it completely. If you applied something to stiffen the rope, you could deflate and remove the beachball and have a "ball of string". That would look very artistic, I guess.
I don't know if a beginner should try a Turks Head with such large stuff, but if you want to try something like a Turks Head, I can help with templates and such. I have posted templates to tie spherical Turks Heads with small stufff using toilet paper tubes as a mandrel. You should practice with small stuff before you try to tackle a big project. The templates are a
www.khww.net in the tutorials section if you want to take a look. In the gallery section, on page 2 of the personal galleries, you can see some photos of spherical work I have done. The templates can be scaled up to suit, you will probably need a concrete tube mold (avalable at Home Depot) for a mandrel if you want to use a template method to tie a spherical Turks Head. If you live near Seattle, I would love to "hands on" help with this kind of project, otherwise, I can only offer written instructions and encouragement.
Pat