While there are a number of ways to attach the lenses inside your bucket, I found the easiest and fastest is to use a product called SUGRU.  It is a kneadable glue, sort of like play-doh (plasticine) that is super easy to work with, and will hold forever.  It does keep somewhat of a pliable consistency after drying, can be removed if you ever need to and does not emit heat during the curing process like CA or Epoxy glue. It is available online (like here on Amazon) and in many craft shops,