Pixelmon Mod

Chalk is used to make the outline of battle arenas.

Despite chalk being a soft sedimentary rock in real life, Pixelmon's could be made by crafting Diorite with something else (ideally something to 'soften' the Diorite) and give a stack of 16 for each block of Diorite - logic there being blocks are 16 pixels tall and when placed chalk would lie flat like redstone. Placeing it down into the world would use the exact same logic as redstone with it connecting to itself in lines, at right angles, 3 and 4 way intersections, and over increases in height of one block tall.

This was inspired by how some stadiums look in the anime. Do a google image search of "pokemon anime stadiums" to find some examples.

Interesting tool for building.

Could maybe expand that to colored variants - at which point you can just name it "Marking" or "Trim".
I could see it crafted from 3 Honeycomb + 1 Dye (wax based), and/or 1 Silicone + 1 Dye (polymer based), more akin to the slightly raised road markings than chalk lines.

... maybe even variants that glow in the dark (emissive textures, no light source), crafted by mixing a Glowstone Dust into the recipe? (Can be expanded to using Glow Ink on existing ones in future versions.)

Ooooo including a recipe to make an emissive version or a version with a light level of 1 is a great idea. Would make battles at dusk or night super pretty.