Hi guys. 

Looking for any ideas to create the 3rd tier / the bucket. Please please help

I would probably use rice krispie treats and a layer or two of ganache or candy melts to give it stability.  Then proceed with decorating.

Or if it doesn't need to be edible you can always make it from styrofoam.

Nothing wrong w/what  Freckles said, but You could use all cake by making one layer complete, then cut out the center in another layer, ice the top & stack them.  Or cut/torte the 2nd layer before cutting out the center so it's only 1" deep.  If the layer is an 8" I'd cut the hole only 4" or 5".   A 6" hole probably won't be strong enough laying on it's side like that.   Crumb coated in ganache it should be strong enough.

I think either suggestion would work.  If you choose to use cake, it might work better, and I think look better, to make the paint can a little smaller in proportion to the tier below it.  In the picture they appear to be the same size.  I would go two inches smaller for the top tier.