Basically everything above, it's all good advice.
Also, no tape or any other adhesive products like it. Very dangerous.
Basically, if they can find it, they will eventually. Good rule of thumb: if you have ANY doubt as to whether or not it's safe don't put it in the enclosure.
There are plenty of horror stories out there. If you have any questions or doubts ask before you use it and we'll make sure you don't become one of them.