Based on the answers provided, the model needs to make the following corrections to the 3D object:

1. Attach a slim, isosceles trapezium to the rectangle. The base of the trapezium should be about 2/3rd of the length of the shorter side of the rectangle.
2. The angular sides of the trapezium should be about 1/10th of the length of its base. 

Please ensure that these changes do not affect the existing rectangular shape of the main body and its extrusion.