Lately I've been using color-tips along with the Night-Writer for basically all of my light-art photos. The colors work well and I like drawing with a slightly diffused light-source - it's easier to properly expose the image when the light-source isn't blowing out part of the detailed illustration.
One thing I've been doing that helps to diffuse the bright LED on Night-Writer (when I'm not using the color-tips) is to rip off a piece of paper (usually from an old receipt or whatever I had in my pocket at the time), place it in the recessed tip area and presto - a duller light-source.
I have been doing this for a few months now, enough that I've decided to go ahead and produce some semi-opaque white color-tips. I think from now on I will include one with every Night-Writer order. It's useful for diffusing the light and gives a great 3D texture:
Location: Los Angeles, CA / Settings: F.11, ISO 100, 21 seconds
My results are kind of interesting - it's basically like getting in 2 drawings for the energy of one with regard to battery use.
Use the LED light for the first drawing, and this charges the glow for your second drawing - I've illustrated some Yin and Yang symbols to demonstrate the idea:
Location: Kitchen / Settings: F4.5, ISO 1600, 21 seconds each
I may offer these as additional color-tips for the Night-Writer soon. There is still some testing to be done with them, and the red glowing tip smells pretty bad (like sulfur), but I like what direction this concept is headed.