Someone sent me this picture, wanting me to make the cake. Uhhh...this might be a little over my head.  I have no idea how they made this can.  Any ideas? I assume it's fondant, but it looks so much sturdier than fondant.

Pic is the one on the far right, sorry I didn't realize it was a banner.

I would make it out of an 80/20 gumpaste/ fondant mix.

Purchase a new, empty paint can from Home Depot, wrap it in wax paper and measure the height.

Roll out a sheet of the gumpaste/ fondant mix to about 1/4 of an inch thickness , trim it to the height and actually wrap it around the can.

Let dry a day or 2, slide it off carefully and let the inside dray another day or 2 before decorating it. 

~ Not sure if that is how they did it, but that's how I would 

AThat might be done with pastillage.

http://forums.egullet.org/topic/69493-demo-intro-to-pastillage/

Granted, I've never worked with fondant a second in my life.  Or gumpaste.  But, I've built plenty of things from other materials :)  I think I would do something similar to what Melanie above suggests, but I would use a styrofoam core for security.  I'd cut the cylinder a few inches longer than the length I wanted the can to be, then make a cut to where one piece was enough shorter than the finished can will be to provide room for the rainbow ribbon pool.  Then I'd dowel them together, wrapping the top piece in parchment/wax paper/something the fondant won't readily adhere to.  Form the can around the styrofoam, and once it has dried enough, ease the dowel and top portion out of the can.  Having the extra structure inside the can would make me feel safer, I think.  But, there are probably 20 reasons why this is a bad idea that experienced folks will hopefully point out!