Attempting to re-create a pickaxe in The Lion King mod for 1.12.2

Hi guys and gals,

It should be noted that I have very little java experience.

I'm attempting to make a pickaxe that takes down a 3 by 3 area (but not ores) similar to the one you can acquire in The Lion King mod for 1.6.4 Minecraft.

The code for said pickaxe is here https://pastebin.com/ju8iz6Kq

I have the code ready to be edited in MC Creator but I'm unsure on where to start in different parts of the code. If anyone could lend a hand, that would be amazing (or even a link to a mod for 1.12.2 that does what I'm after)