This is one of my favorites.  It started life in the Plasticville model factory as a diner, but we've added plenty of detail to change it into the local fish place.  It was primered dark gray and then dry-brushed silver to get the look of an older diner.  Thenk it was thoroughly rusted out with our "streaky rust" technique.  As always, some vandal has added commentary about this particular "grotto".

Cap'n Skippy's Seafood Grotto

The advantage to using model railroad kits as building shells is that you get a building roughly in scale relatively cheaply.  The disadvantage is that some of the parts sometimes don't have a lot of detail  That was the case with the roof.  So it was primed black and dry-brushed dark gray with streaks of brown.  Lines were painted back on in black to simulate the roof being made of seperate panels.  There are no molded-in lines, the "seperate panels" are purely an illusion.  Then, we soaked some squares of paper towel in white glue and placed them on in a patchwork pattern. They were then painted black and dry-brushed grays and tans to simulate tar-paper patching. 
The anchor was purchased at a craft store, and the fishes came in a party-favor pack for about 5 cents apiece.  Some were impaled on dark nails, which were then epoxied onto the roof.  The overall effect being tacky fiberglass fishies mounted atop a restaurant as a crude sort of signage.  

The back was rather plain, so it was thoroughly rusted-out for interest...... 

The interior features everything a diner should have: grungy eating area, a counter, the register, etc.  Wall decor consisted of cutouts from magazines, dollhouse bits, model RR bits.  The "net" was actually a piece of gauze dipped in strong tea. 

It's kind of hard to see, but the grill has a small cage on it containing a frog, who is apparently next on the menu.  The yellow morass is the "Tub O Chowder" which is actually never cleaned out.  It is perpetually on the stove, and "stuff" is added to it daily.  Stuff like curdled milk, day old bread, fish heads, you name it.  Mmmm-mmm.  I can smell it now!