dkh2,
I used a pencil for size and punched 3-4 openings per cup, careful not to break the styro cup. It worked ok, but nothing as well as BB uses. I needed the constant water wick from the bottom of the cup and needed to move the trailer in and out of the weather. On days with lots of sunshine, I placed a shade cloth over the trailer and removed it on cloudy days.
I used a pencil for size and punched 3-4 openings per cup, careful not to break the styro cup. It worked ok, but nothing as well as BB uses. I needed the constant water wick from the bottom of the cup and needed to move the trailer in and out of the weather. On days with lots of sunshine, I placed a shade cloth over the trailer and removed it on cloudy days.