I go on your foot to keep it warm and comfy. You wear me before footwear. What am I?

I glide through the shadows where the sun cannot shine, With a thick steel skin and a path in the brine. I have no wings, but I fly through the deep, Sailing past monsters and mountains asleep.

It comes for free with the items inside, though most recycle me. Dioramas are made in me, things can be stored in me. What is this reused item, often repurposed?

What do Gungans store items within their homes? In

I slip through spaces, tight and small, Yet I am not a worm at all. I help keep teeth both clean and bright, by reaching spots beyond your sight.