Can inset faces be used on a triangular face? I have a triangular object created by merging two edges of a cube.  The object is a thick triangle of constant thickness.

I would like to do an even inset one of the triangular faces.

When I try the inset lines cross an
To inset... Use the inset tool.

Select the faces and Press I and drag to get the desired width.



Be careful to avoid making the inset much wider than the distance to the center of the face, or you'll get errors like these: