STEP-BY-STEP ASSEMBLY :
Step 1. Join part 1 and part 2 by part E first, then join part 1 , part 3 and
part 4 by part B .
Step 2. Join part 3, part 4 and part 5 by part E first, then join part 6 and
part 7 by part F , then join part 4 and part 6 by part C .