https://community.graphisoft.com/t5/Libraries-objects/ceiling-lights/m-p/141856#M22613 You might try this:<BR /> Substract the ceiling light from the slab using Solid Element Operations. This way the substractions remains with light and you can move it around. Sun, 22 Nov 2009 21:42:54 GMT Anonymous 2009-11-22T21:42:54Z https://community.graphisoft.com/t5/Libraries-objects/ceiling-lights/m-p/141855#M22612 <DIV class="actalk-migrated-content"><T>Hello….<BR /> I want to create a ceiling light. Is it possible to automatically subtract the “slab” when a place it or move it? I want the light to behave like a window on a wall……<BR /> <BR /> Thank you…</T></DIV> Wed, 24 May 2023 09:55:44 GMT https://community.graphisoft.com/t5/Libraries-objects/ceiling-lights/m-p/141855#M22612 Anonymous 2023-05-24T09:55:44Z https://community.graphisoft.com/t5/Libraries-objects/ceiling-lights/m-p/141856#M22613 You might try this:<BR /> Substract the ceiling light from the slab using Solid Element Operations. This way the substractions remains with light and you can move it around. Sun, 22 Nov 2009 21:42:54 GMT https://community.graphisoft.com/t5/Libraries-objects/ceiling-lights/m-p/141856#M22613 Anonymous 2009-11-22T21:42:54Z https://community.graphisoft.com/t5/Libraries-objects/ceiling-lights/m-p/141857#M22614 Just one more addition. If your lamp is hollow on the parts in the slab, you may want to consider creating a solid model variation for the subtraction operation. You can branch the two models based on the (GLOB_CONTEXT &gt; 40) condition.<BR /> <BR /> Regs,<BR /> Zsolt Mon, 23 Nov 2009 08:07:07 GMT https://community.graphisoft.com/t5/Libraries-objects/ceiling-lights/m-p/141857#M22614 ztaskai 2009-11-23T08:07:07Z