I plan on cutting a piece of 1/8 in. board I have to fit the top of each section. The only way for them to escape is to push the front open with their head. How I am going to remedy that is to get those little things that will swing down and block the drawer front coming open. Sorry im not sure what they are called lol. I gotta make sure there is absolutely no way for them to escape before I actually move them in tho. Im also open to any other ideas.

Here is a pic of one of my males in it.