inkstone case; inkstone box
A traditional box for storing calligraphy tools, especially the inkstone (硯). Often part of a larger set (硯箱) used in Japanese calligraphy.
My grandfather's inkstone case contained an old ink stick and brush.
文箱 is a general document or letter box, not specifically for calligraphy tools.
Standard kanji spelling.
Search-only kanji form; not a standard spelling.
Rarely used kanji form; 筥 is an uncommon variant of 箱.
Compound of 硯 (suzuri, 'inkstone') and 箱 (hako, 'box'), with rendaku voicing of 箱 to ばこ.