The drawing of the pattern envelope, use the following measurements (in cm): 

1. The length of the envelope 130 
2. The width of the envelope 75 

The drawing of the pattern of the plotted rectangle АА1А3А2 (Fig. 61) . Side AA1 and А2А3 equal 
measure the length of the envelope 130 cm Side AA2 and А1А3 37.5 cm - 1/2 measurements of the width of the envelope (75 : 2 = 37.5 cm). 

From point A2 up put 20 cm and the point A4. From this point, the right will draw a horizontal line to the intersection with the line А1А3. The point of intersection will be denoted by A5.

From point A to the right set aside 25 cm and the point A6. From this point drop a perpendicular to the line А2А3. The point of intersection with the line А4А5 denote the A8, with a line А2А3 - A7. 

The distance between the points A6 and A1 divide in half and put a point A9. From this point drop a perpendicular to the line А2А3 and the point of intersection denoted by A11 and a10. 

The top of the envelope. From point A4 put 6 cm along the line dividing the angle in half, and put an end A12, cut А4А8 also divide in half and put the point A13. Point A, A12, A13 connecting concave smooth line.

The pattern to be cut along the contour And, A12, A13, A8, A7, a10, A11 and A5.