How do I place bricks into a grid?

I am attempting to create my own basic stamper tool, I have created a hopperbin and put this into a local script.

script.Parent.Selected:connect(function(M)
    M.Button1Down:connect(function()
        if not M.Target then return end
        x = Instance.new("Part", game.Workspace)
        x.Size = Vector3.new(4,4,4)
        x.FormFactor = "Symmetric"
        x.Position = Vector3.new(M.Hit.x,M.Hit.y,M.Hit.z)
        x.Anchored = true
    end)
end)

I've gotten it to the point that it creates the brick but they are not really well organized. I know that with the ROBLOX stamper tool the bricks move in a sort of a grid fashion, How could I achieve that with my basic stamper?