Step 1:
Each birdhouse is made out of three a4-size papers, two white papers and one colored.
The colored one (yellow) is for the roof.
Glue/tape two white papers together.

Step 6:
Valley-fold over these two lines.
Then unfold the model.

Step 5:
Valley-fold over these two lines.

Step 2:
Lay the yellow paper in the center, see picture. Glue or tape it to the white papers and cut along the blue line.

Step 4:
Prefold over these two lines.

Step 3:
Now you've made one large rectangular Origami paper.
Prefold over these two lines, then turn the paper.

Step 10:
Valley-fold over these two lines.

Step 8:
Valley-fold over these four lines. The corners indicated by the arrows are pulled upwards when you do this.

Step 9:
Press these four places flat.

Step 7:
Fold over these two lines, the valley-folds are already prefolded.

Step 16:
Pull the parts on the right and left upwards by folding over the short blue lines, the lines in the center are valley-folds and the two outer lines are mountain-folds. Make the same folds on the other side, see arrows.
Valley-fold over the two yellow lines while you do this.

Step 15:
Press the layers between the two large arrows against each other. Then fold them together over the blue line.
Do the same on the other three flaps, see small arrows.

Step 12:
Pull these four edges outwards.

Step 11:
Valley-fold over these two lines.

Step 14:
Make an inside reverse fold on the four corners. Valley-fold over the two yellow lines while you do this.

Step 13:
Prefold over the two yellow lines first, they are used as guidance to place/make the prefolded blue lines.

Step 19:
Turn the model.

Step 18:
Valley-fold over the two diagonal blue lines and mountain-fold over the other two.
Valley-fold over the yellow line while you do this.

Step 17:
Mountain-fold over these two lines.