To begin, follow this link to access SelfCAD software and launch it. https://www.selfcad.com.

Then:

•  Select a Standard Primitive - Cylinder
•  Set the following parameters:

1. Top and Bottom Cylinder radius 40
2. Height 10
3. Horizontal Segment 2
4. Vertical segment 24
5. Arc 360

• Rotate it by 90 degrees 

• Make 2 copies with Copy Offsets Tool:       

1. For first model set value 200 on axis X 
2. For second model set -100 on axis X

• Scale the middle copy and set values:  

1. X: 195
2. Y: 70 
3. Z: 70 

• Select and isolate middle object from other objects

•  Make two copies with Copy Offset Tool
• Scale copied objects with values:

1. X: 210 
2. Y: 65
3. Z: 65

• Hide copied element

• Select main and copied object and use Stitch and Scoop
• Than use Difference option and select copied object 
• After that isolate differenced object

•  Select visible cylinder. 
•  Choose Cube Selection tool and make selection with values:

1. Left 5
2. And Right 198

• Use face selection mode and choose top faces with help Right Button Mouse and then delete them

Use Add Thickness tool with value -2,5

• Choose copy and use Move tool to transfer it on 150 on axis X
• Then make it a little bit smaller using scale with values: 

1. X: 209 
2. Y: 64 
3. Z: 64