Attachng the baffle to the other enclosure. Hint: Clamp it near the four corners so that it overlaps the sides all around. Drill the pilot holes for the screws while it's clamped (or it may move while you're drilling). Remove it, apply glue, screw down tightly, wait until dry. Then (yet to be done with this one) you can use your router with a trim bit to trim it flush with the sides for a professional looking fit.