a detailed line drawing for coloring, featuring a whimsical scene where a cartoon-style black cat is happily engaged in building a sandcastle on a sandy beach.

Beneath a bright sun, a playful black cat with a cheerful expression dons a floppy sunhat, eagerly sculpting a grand sandcastle with its colorful bucket and shiny spade nestled beside it. In the background, the gentle ebb and flow of the ocean waves mingles with the cries of soaring seagulls, creating a lively seaside atmosphere filled with joy and anticipation.