Step 7: The Elements
Waterproofing - if you are re-cycling a home audio speaker, you probably want to paint it. a PA or DJ speaker normally has a waterproof box. In either case, i found the woofer cone is often made of unprotected stiff paper. You can easily waterproof this by coating it with a thin layer of a water-based urethane wood finish - such as Varthane - from your home improvement store.
Vibration proofing - i'm making mobile bike systems, these get vibrated a lot. amps often have some larger components in them that may or may not be well attached to the amp board. take a look and glue down anything that looks flimsy. hot-melt glue and silicone glue both work well to glue down any wobbly parts in your electronics. some of the T-amps are ok. the ones from arjenhelder_electronics needed some anti-vibration glue (see the photo). the original TK2050 from sure electronics also needed a bit of help.