To plot an iso-density boundary of a topology optimization result:
Select the Post page.
Select the contour panel.
Click simulation= and select the last iteration step to plot.
Click data type= and select Density.
Click contour to see the density contour on the undeformed structure.
Select the isosurface subpanel.
Toggle legend based to value based.
Click on include faces above.
Enter a value, say 0.3, into iso surface=.
This is the density threshold.
Click on show.
The density threshold can be changed by either using the add/sub buttons or by using the slider in the legend.