How Would I Do This?

I know this is sort of a request but how has loleris made it so in TMM (The Mad Murder) under the hatch there is a brick and if you don't have the access, the brick is there, and if you do it is removed for you only and still there for others who don't? I have tried cloneing bricks to a player's PlayerGui when they join and other places so only certain player's do not see it, this is what I have but how do you do it properly:

allow = game.ServerStorage.Allow
deny = game.ServerStorage.Deny
Permission = {"UndiscoveredLimited","Idontcare2004","moonmim","Amy21227","funkstaducksta"}

game.Players.PlayerAdded:connect(function(p)
    for i = 1,#Permission do
        if p.Name == Permission[i] then
            a = allow:Clone()
            a.Parent = p.PlayerGui
        elseif p.Name ~= Permission[i] then
            d = deny:Clone()
            d.Parent = p.PlayerGui
        end
    end
end)