This is the recipe I use for the blender pen refill:
1 part glycerin (can be found at walmart)
2 parts distilled water
1/4 tsp of rubbing alcohol
Or you can use this one:
2 tablespoons plus 2 teaspoons glycerin
5 tablespoons water
1 teaspoon rubbing alcohol
This can be really messy, so store it in an airtight container... Even those have a tendency to leak... I use one of the tiny tupperware cups. I have had my refill mix for a really long time--just that tiny little bit!
If you use the refill recipe with your ink refills, I personally like to just dip the tip of the aqua painter into the blender pen refill and mix it on a palate with a small amount of ink (instead of filling the painter with the blender refill fluid). I usually have scratch paper to the side to dab off the extra ink and to play around with the colors. I also have a small container of water to rinse the painter off.. Give it a try!!