Development Assistance Help with 3x3x3 Pickaxe (MOD)

I am making a mod and for my pickaxe i would like it to mine a 3x3x3 if you have any ideas or you know the code please help! Here is my current code:

Code:

package com.idtech.item;

import com.idtech.BaseMod;

import net.minecraft.creativetab.CreativeTabs;
import net.minecraft.entity.EntityLiving;
import net.minecraft.item.ItemPickaxe;
import net.minecraft.item.ItemStack;
import net.minecraft.util.BlockPos;
import net.minecraft.world.World;

public class ItemGelPickaxe extends ItemPickaxe {
  
      public static final String name = "GelPickaxe";
    
          
    
      
    protected ItemGelPickaxe() {
        super(ItemMod.toolMaterialGel);
        // TODO Auto-generated constructor stub
        setUnlocalizedName(BaseMod.MODID + "_" + name);
        this.setCreativeTab(CreativeTabs.tabTools);
    }

  
  
      
      
    }
  
  
  
    

Thanks,
Charles (Java Town Owner)