You can make them out of two twelve volt Bulbs similar to the ones In the brake lights. Wire both grounds together and then the other two wire are a signal wire for each bulb. Get the pin out for the TPS sensor and make the connections.

 

Here is how I built mine. I used 12v leds and a small case. Depending on the led, you might need to swap wires. They don't label the ground in some cases.