Converting Blender Model into STL format for 3D rapid prototyping

The first thing that had to be done with my stage model mounds was to stitch their faces up entirely so that I would produce a solid mound for both pieces.

This was done by being in edit mode. Have the magnet icon activated/4 vertices selection button on/ E (extend vertices down to a common flat base distance)/ Z/ CNTRL+hover over vertice I want to pull my vertice down to it's position in the z axis.

This was done for all vertices at the base and then they were stitched together using faces (SHIFT+select up to 4 vertices then F (faces)).

I then had to check that all of the normals were facing outwards so as to be able to be 3D rapid prototyped. This was done in edit mode of the object/ Mesh Tools More/ N size:1.5/ have Draw Normals selected. Be in face selection mode/ right click on the face that has the normals facing inwards/ EDIT button (4 vertices in square)/ Mesh Tools/ Flip Normal. Repeat for all faces like this.