AUTOCAD Elbow joint-Square Cross Section Practice Tutorial for beginners

Here is the step-by-step procedure for creating the 3D elbow model with flanges at both ends:
Create the Flange Base (Top Plane)
Start by drawing a square on the Top Plane (XY Plane) with dimensions 50mm x 50mm. Inside this square, create a circle at the center with a diameter of 24mm. This circle will represent the internal hole of the elbow. Then, extrude the square (with the circle inside) to a thickness of 5mm to form the flange. The flange will have a thickness of 5mm.
Create the Elbow Profile
Switch to the Right Plane (XZ Plane). Draw a quarter-circle profile with an outer radius of 50mm and an inner radius of 24mm. This profile represents a hollow elbow, with a wall thickness of 3mm.
Extrude the Elbow Profile
Extrude the quarter-circle profile along the X-axis to form the 3D elbow. The extrusion should create a hollow section of the elbow with a wall thickness of 3mm and an internal diameter of 24mm. The extrusion should match the desired length of the elbow.
Position the Elbow to Align with the Flange
Align the extruded elbow with the flange. Ensure the center of the elbow aligns with the center of the internal hole in the flange. The elbow should be extruded along the right-hand side (positive X direction), facing the right side.
Add the Flange Holes
On the top and bottom faces of the flange (the 50mm x 50mm square), create four circles with a diameter of 5mm. Position these circles at the corners of a square, with a side length of 41mm, inside the flange. Extrude the circles to cut through the flange, creating holes with a 5mm diameter.
Copy the Elbow
Once the first elbow is created, copy the entire elbow part, including the flange, to produce a second identical part.
Rotate and Position the Second Elbow Part
Select the second elbow part and use the Rotate command. Rotate the second part 90 degrees around the Z-axis to place it perpendicular to the first elbow part.
Join the Two Elbow Parts
Align the two elbow parts at the ends so that they meet at a 90-degree angle. Use the Join command to combine the two parts into a single, connected 3D model.
Finalize the Model
Review the model for accuracy. Ensure that both elbows have flanges at both ends, the elbow has a wall thickness of 3mm, the flanges have a thickness of 5mm, and the internal hole of the elbow is 24mm in diameter. Verify that the flange holes are 5mm in diameter and are placed in a square pattern with a 41mm spacing. Double-check that the two parts of the elbow are properly rotated and joined at a 90-degree angle.