Gary,
Since you have finished the build you'll have to mount it differently. Go to the hardware store or home improvement store and get a couple "lamp Finalles"....I know bad spelling. The brass things that go on lamps, I have even found turned wooded peices in the section where they have the wooden trim in the home improvement stores.
Take the brass or wood peices (2 should do) and attach it to your base (wood screws should work fine) as a trial to make sure everything is straight and looks good. Take those peices off the base and epoxy them to the bottom of you build, let dry then attach to the base.
The epoxy should be more than enough to hole the build to the base, I've use this way a few times because I always forget to put screws in the hull before I close things up.