Answer:
An art-form and its colourful result.
You can have it, and be at it, But it never lasts forever.
Other terms for this handy device include doohicky, doo-dad, and whatchyamacallit.
What goes up and down without moving?
What hangs in the sky by day but at night goes away?
If it’s information you seek, come and see me. If it’s pairs of letters you need, I have consecutively three. What am I?