Why doesn't position, vector3, or CFrame work for this on line 11?

So I'm trying to make this part practically follow the players torso but when I make it try to update and follow it doesn't work..

local Player = game.Players.localPlayer
game.Players.PlayerAdded:connect(function(plr)
	plr.CharacterAdded:wait()
	plr.Character:WaitForChild("Torso")
	local torso = plr.Character.Torso
	local part = Instance.new("Part", game.Workspace)
	part.Transparency = 0.2
	part.CanCollide = false
	part.Size = Vector3.new(4,4,4)
while wait(0.1) do
	part.Position = CFrame.new(torso.Position)
end
end)

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