I am using color axis water-based color pens. The grip is cut into 4-2-7 blocks. The following is a template for when selling modified pens: Since this was made or purchased over 10 years ago, I cannot guarantee the spinning feel, completeness, usability, scratches, or stains. I will try to indicate the presence or absence of substitutes as much as possible, but there may be memory errors. Please understand the above before purchasing.