This is a purely Photoshop tutorial.
The attached files: Spell_Icon_Resources_v01.zip
...are intended to serve as a help to modders who include new spells in their mods to create new BG1-style spell icons in a streamlined process, or improve spell icons in their existing mods.
Basic overview: New spell icon designs must be created first. They are then inserted in bulk in the Master Template, correctly positioned in the grid and and relative to the scrolls, and exported into corresponding color BAM-derived PNGs. C, A and B are created in this same way, in that order