Oblique sections are useful to show this:

In oblique projection, important shapes should be in this position relative to the viewing plane:

If a complicated pictorial is needed, it may be easier and more accurate to create a 3D model than an oblique drawing.

In oblique projections, the projectors are perpendicular to each other but are not parallel to the plane of projection.

In a CAD system, you can draw an ellipse by specifying these:

Oblique drawings are dimensioned in a similar fashion as these types of drawings:

If you are sketching an ellipse in an oblique drawing, you can block in the enclosing rectangle and sketch the ellipse tangent to its sides.

In oblique projections, one of the object's principal faces is parallel to the plane of projection.

Circles, circular arcs, and other curved surfaces may be drawn using offset measurements.

In general, all types of sections for isometric drawing may be applied to oblique drawing.

In an oblique drawing, equally spaced partial circles may be used to show this:

When the receding lines are true length, and the projectors are at 45 degrees to the plane of projection, the oblique drawing is called this:

When the receding lines are drawn to half size, the drawing is known as a cabinet projection.

In an oblique drawing, when an angle is specified in degrees in a receding plane, you should convert the angle into circular measurements.

In CAD, oblique drawings are difficult to create because you cannot use snap increments or draw similarly to drawing on grid paper.