Nobody mentioned the DIY Color TV kit that came out in the fifties....it was a colored plastic film that you applied to the TV's picture tube and gave you blue skies....well, maybe....and green earth...well, maybe...if the film's colors just happened to coincide with what was being televised...
How about the magnifying glass you would put in front of your TV so you could see your 17 incher as if it was a huge, never heard of 21. If you had both, the color and the magnifying kits you were set for the summer.