Once you have decided to build these lights, you must decide how many LED's and which ones you will use. I went with 8 LED's, 4 in each hood and it turned out perfect. Determine which LED's you will be using and what your power source will be. The LED's I used were rated for 2.8V@20mA. My power source was an old wall wart that was rated for 6VDC@100mA. Make sure to actually test the voltage coming out of the supply as mine was up at 9.9V! Don't forget that when you work with LED's you need to limit the current by using resistors in the circuit. You could do all the math, but being lazy, I used this site
and it worked awesome, just plug in your numbers and it does the rest.
Now you have to determine how to mount the LED's. I simply drilled holes for the LED's in the existing fluorescent mount, however your hood may differ.