Modular building structures comprised of extruded components

A modular wall structure comprising:

• a plurality of horizontally-oriented wall panels connected together in a substantially vertical stack, each of said wall panels being an extruded, synthetic component having at least one interior hollow, at least one receptacle, at least one protrusion, and at least one outer portion angled relative to vertical to simulate at least one row of horizontally-oriented siding;
• a first fastening panel connected to a left edge of said modular wall structure;
• a second fastening panel connected to a right edge of said modular wall structure;
• and
• a reinforcing member extending through one of said at least one interior hollow in one of said wall panels, said reinforcing member having a left end portion secured to said first fastening panel and a right end portion secured to said second fastening panel;
• wherein adjacent wall panels are connected together by inserting said at least one protrusion of a first adjacent wall panel into said at least one receptacle of a second adjacent wall panel.