best way to create the access holes

[JJ1]

Ron, yours is a great web site and I have learned a lot. I can see you get a lot of the same questions over and over. Now I searched for an answer to my question, but could not find it maybe you can direct me to it. the container that holds the solution for the 11 plant unit - what is the best way to create the access holes - I am concerned that the plastic lid will crack and crumble. thx j