From the left, number pieces 1 - 18 (8-18 are the same)
Arange pieces 4-5 and 8-11 like this
Add pieces 12-13, you will need to open one side to do this
Add pieces 14-15 and 3 goes in the middle
Slide 4 and 5 down like this
Add 16-17
Add 6-7 with the notches facing the same way as those of 4 and 5
Add 18 like this
Slide 4-5 back up
Add 2 and 1 and it's done
