Tutorial on animated sliders, knobs etc.

[MerryOtter]

If he creates 1 knob, then clones that knob and rotates it 90 degrees.... All he needs to do then is convert the blend to editable shapes and ungroup for many versions of the same knob.

As both your image and my image shows, the knobs get smaller in the middle of the blend. Furthermore, if you look closely in the example below, you see that the little "marker" on the knob is not actually being rotated, it's moving along a straight line (and the distance between it and the edge of the knob is changing).

A copy of your image with selected knobs highlighted shows they do not look alike.

He would do better to use the blend tool between two identical, unrotated images, break it into editable shapes, ungroup, and apply the rotation individually. But rotating the ending knob and blending is definitely not an option.