OK, next time try be more specific in the question... It kinda confused me, like you were purposely trying to obfuscate the question.
I know how to do it in a 1 script, but it'd be easier to explain this way.
OK, pretty simple really.
Put a script in the Part that you want to be visible in an area.
Change the script from print("Hello World!") to this:
while wait(0.05) do
if script.Parent.CFrame ~= CFrame.new(xAxis, yAxis, zAxis) then
script.Parent.Transparency = 1
else
script.Parent.Transparency = 0
end
end
And now, to put the brick in the player's Camera, you'll need a localscript.
You can use this script for the localscript, unless you want something more complicated, then make your own.
LocalScript:
Part = PartLocationHere
Part.Parent = Game.Workspace.CurrentCamera
Well, I hope this helped.