Finesse Blender Pen for Colored Pencils, Pack of 3 | Global Art - Cheap Joe's Art Stuff
The Chameleon Pen – Double-Ended Colorless Blender Pen – Daytomax
Amazon.com : Alcohol Colorless Blender Marker Dual Tip Pack of 3 - Colorless Marker Blender with Japanese Ink & Brush Tip - Clear Blending Pen for Art Illustration, Portrait, Sketching, Drawing :
Blending markers 2 ways: Which is better Blender Pen or Water Brush? - Smiling Colors