Have you ever bought a scale building or wanted to build an addition to one you found on eBay?  Just go down to the local floor tile store and purchase of the older style, not ceramic, floor tile.  Take it home and score lines across it about 1/2 inch to 3/8 inch apart.  Make sure the lines are cut in the tile deep enough to let the tile break alond the line.  Then support the tile on a nice straight edge and break the strips off.  After that break each strip into 1/2 inch long lengths and you will have a pile of small broken tiles.  Start with super glue and build the walls like the prototype stone masons do and work up overlapping each joint.  When you come to a window or door use longer tiles to place across the bottom and across the top to bridge the opening.  Finish to your required height and once at the top sand the top and bottom edges flat.  When doing the edges of the walls, leave enough room to insert blocks from the next wall so as to make a strong corner when your wall turns to what ever angle you want.  Doors and Windows can be found on eBay or Hobby Shops from Tichy, Grandt Line, or many other makes of fine castings.  The stones can then be painted the proper colors that you want or if you start with a gray, or rust colored you may want to leave it alone with the broken edges nice and crisp.  In any case, this is a technique to replicate stone walls without having to either distroy existing poured castings of metal or plastic, make custom walls or structures.  You can get premade tiles from several locations on eBay as well.  One such seller calls them Baby Building Blocks.

This technique is used by several large and expensive kit manufactures to make the masters to what eventually becomes their cast metal kit walls.  Now you can make the walls to fit your needs and never be limited to a kit design again.

Thank you for reading this and be sure to see other helpful hints on my site as well at SierraScaleModes.