If you want the shape seen in your image, draw its contour with thin walls in a new document, rounding the wall matching the top part, and set the color of the both sides of the bottom part with a different color.
Then select the 4 walls, choose File > Export to OBJ format menu item and the option Export selection when prompted.
Once the OBJ file is exported, import it with the Furniture > Import furniture menu item. During the second step of the import wizard, rotate the shape to get the round part at top, and during the third step, select the Door or window option.
Place the imported shape on a wall and finally, change the material of the bottom part to make it transparent. You'll get the result in the attached file.
You could also read this guide which explains how to define the cutout of a door.
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ArchFrame.sh3d
(75126 bytes)
(Download count: 186)
(Arch frame built from a shape drawn with thin walls)----------------------------------------
Emmanuel Puybaret, Sweet Home 3D creator
