I modified the model by removing seam lines in various places, adding panel lines, and using sprue to add spacers to the waist for improved articulation.
The track links were also widened by inserting junk parts in between.
All painting (including the primer) was done with water-based hobby paints using a brush.
A water-based weathering paint wash was applied as a finishing touch.

HG Guntank fully painted with a brush (Shimizu-style brush painting practice) | ダイ's Gunpla works