Robby, the liner interlocks when you close it. After a few humidors I have perfected it. I use my router to make the groove just short of halfway in the top and bottom pieces. I don't normally glue the liner. I just cut it so I get a pretty tight fit. I put the cedar in and test it. Initially, it should not close. I can see where it's binding. I just sand a little off the joint until I can close the lid with a little pressure. I can drop the lid, and it will not shut all the way. It takes that little extra push. Good seal? Puff? Squeak? Oh yeah!