How to add tiny floating 3D axes to a 3D plot

I have a 3D plot (below) with very fine features. I would like to zoom in to one specific area and have a floating 3D axes there to show the scale. I know you can plot additional 2D axes on a plot, but I haven't seen a way to add 3D axes.

Answer 1

[Image Analyst]

Did you try to set the axis locations to origin?

ax = gca
ax.XAxisLocation = 'origin';

Or else simply use line() to draw those black lines wherever you want them.