<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hello everybody,<br class=""><div><font color="#5856d6" class=""><br class=""></font>I hope it works now.<br class=""><font color="#5856d6" class=""><br class=""></font>I have attatched a stripped down case of the problem. You will find the *.geo file as well as the *.stl file in the compressed folder. Your remark seems to imply I need to get the id number of the faces I want to extrude directly from my *.stl file. Are the faces consecutively numbered? I guess not, because gmsh doesn’t accept identification numbers like 0, 1, 2 or 3. I think the problem is I just do not know how to “activate“ my stl in gmsh.<br class=""><font color="#5856d6" class=""><br class=""></font>Best regards,<br class=""><font color="#5856d6" class=""><br class=""></font>Kate</div><div></div></body></html>