The 470 ohm is there to drop the voltage on one LED.
You could connect 100 like the first schematic I sent you and they would all be just as bright as each other. The +12v feed remains constant all the way down the line, i.e. each resistor leg is in effect 12v, the 470 ohm resistor drops the voltage to 2.2v and allows 25mA of power to enter the LED.
If you connect more than 1 LED in series to a single resistor it will be a lot dimmer, progressively until it wont light at all.
To light them in series (cathode to anode to cathode etc) you'd need a lower resistance resistor. For example to connect 3 of your orange in series you could wire up 2 resistors in parallel to feed your circuit. Thus:-
Resistors in parallel calculator
http://www.1728.com/resistrs.htm
LED in series calculator
http://led.linear1.org/led.wiz
Connecting 3x 470 ohms in parallel drops the line resistance to 150 ohm which would power 4 LEDs. I won't do a schematic for that but it should be easy to visualise as a progression from the one above.
At 5 LEDs you'd have a voltage of 11v which is close to the 12v and you may not need a resistor at all but you run the risk of burning out your LEDs, it is good electronics to always have a resistor in line with LEDs and for the combined voltage drop of the LEDs to be less than the voltage source.
You could connect 100 like the first schematic I sent you and they would all be just as bright as each other. The +12v feed remains constant all the way down the line, i.e. each resistor leg is in effect 12v, the 470 ohm resistor drops the voltage to 2.2v and allows 25mA of power to enter the LED.
Clear perspex orange tinted? Should react well to the light below, and the ambient light from your cathodes. Should glow nicely. I wonder if a slightly irregular shape would refract the light better, perhaps a curved top to the perspex? Is that even possible?