The direction of rotations used when using the Animation feature in Modeler is fixed. Please add controls to reverse the directions of rotation if desired.
The speed at which the frames are displayed is fixed. Please add a control to allow the user to select different speeds.
Speed just depends on the playback frame-rate. I think a better range of options would be :
start angle; finish angle; for each axis
and ability to specify number of frames (not just 20 or 40)