Minecraft's Broken Script Mod 2.0 (The Place Beneath the Bedrock)

armed with my limited knowledge about modern day MC modding, learned entirely through seeing friends play with similar things in making mods, the blood vessel thing is likely some shader magic, playing with the way the game renders certain things and instead of rendering a block texture, superimposing a 3d effect in it's place. I could be wrong on the "how" though.

heck yeah

Oh yeah! I was waiting for this one, awesome!