It says "Pan.Tilt.Mesh" is not a valid member of model?
local dir = "Pan.Tilt.Mesh";
local mac ={workspace.Mac1,workspace.Mac2,workspace.Mac3,workspace.Mac4,workspace.Mac5,workspace.Mac6,workspace.Mac7,workspace.Mac8}
function Clicked()
if script.Parent.Bool.Value == false then
for i,v in pairs(mac) do
v[dir].Transparency = v[dir].Transparency + 0.5
script.Parent.Bool.Value = true
end
end
end
script.Parent.MouseButton1Down:connect(Clicked)

2 comments
Is the name of the instances "Pan.Tilt.Mesh" or is that the location of it inside one of the Mac's?
It goes "game.Workspace.Mac1.Pan.Tilt.Mesh" same for all the other macs.