Here is a great scrip I came across that makes any of your designs or a random batch in to marbles, well with a bit of tweaking that is.
It suggest to make a random batch or to use some files you already have loaded and the just run the script. I found that using a random batch you kinda get hit or miss results, but overall it works really well.
Please feel free to post links to your images you make with this here.
This is one of the best results I got using it and some toying with just two triangles. I'm sure that much more complex designs are possible.