Hello, You might try to use a combination of the general trapezoid volume ("trap") and the wedge volume ("wedge") that would be the daughter of the trapezoid volume. With the correct geometry and position of the wedge this could make the trapezoid parallel sides look slant.... I hope this helps, vesna <div class="gmail_quote">On Fri, Mar 8, 2013 at 6:34 PM, Sonoko Nakano <<a href="mailto:snakano@sfu.ca" target="_blank">snakano@sfu.ca</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello Gate users, Does anyone know how to define an arbitrary trapezoid standing on two "NON-parallel planes" to the Z axis. So far, I can only define a trapezoid standing on two parallel planes perpendicular to the Z axis. Thank you in advance for your help. Sonoko </blockquote></div>