Technological ledges of the details

 Cut the technological ledges of the details

Smear the edges with glue twice

Glue the back parts of the buildings walls

 Press the parts to each other

Mark the line for cutting

Scratch along the marked line by awl several times

Break along the scratched line

Take the piece of sand paper. You can glue the sand paper on the piece of wood.

The line for gluing sand at the 45º angle

Mark the line of cut.