What to make with junk? (Best answer will be chosen)?

Make a portrait of new york city at night.

This is going to sound cliche ; A rainbow.

You could cut out a cloud of the card board, cover that piece in blue bottle caps, and then make the actual rainbow with the broken jewelry or other colored miscellaneous items.

Hope It Helped :D

You would love this website, instructables. People on that site are always making stuff from junk, and posting about it. I, for instance have made some fitted t-shirts by cutting them apart and knotting them together again.

To piggy back from Nicole's answer about the rainbow, I'd say make a laser light rainbow with LED's.

I like this particular one linked third below, where a book is made into a lampshade! Lots of fun.

Sculpture.

A beer dispensing couch

An underpants sail for a miniature boat.