Just over two years ago I did this rainbow needle marble. It's still one of my favourite designs I've done, and I've been planning to revisit it, neon style. I finally did that last night. :)
I used 6 out of the 8 pen Migi Nail Art set in their white box. Most of the pens are neon-ish and shimmery. Last time I did the design I used mostly Migi's silver box, and I think Migi pens are an easy way to approach the needle marble.
Now, I'll admit I had more troubles with this design. I had to go back in and fill in the "needle tracks," where my needle removed polish instead of just dragging it. However, I love how it looks and it was worth the effort. :)