Almost any good idea will suffice, I cut the top off a square medicine bottle that can hold two 9 volts (one spare). I used double back tape to affix it inside the tin. I also used double back tape to affix the amp and speaker jack. I opted to not drill a hole for the jack, but may add it later. I did cut a small "V" to allow the input cord to hang out with the lid closed. I also finished adding batting to the top.