# Solid object subtraction **URL:** \ **Category:** Pro\ **Tags:** sketchup, advice, bug, modeling\ **Created:** [July 3, 2025, 4:28pm UTC](https://forums.sketchup.com/t/solid-object-subtraction/333486 "2025-07-03T16:28:11Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![julia.gdula](https://avatars.discourse-cdn.com/v4/letter/j/b4bc9f/32.png) [@julia.gdula](https://forums.sketchup.com/u/julia.gdula)\ **Post date:** [July 3, 2025, 4:28pm UTC](https://forums.sketchup.com/t/solid-object-subtraction/333486/1 "2025-07-03T16:28:11Z")
![Screenshot 2025-07-03 172408](https://global.discourse-cdn.com/sketchup/original/3X/3/a/3ab2346c95470cd9d74a3582d7f3e3de232bb407.png) I am trying to learn sketchup by following a course, in order to create walls I made two rectangles within each other, deleted the middle and used push pull, now I am trying to subtract a solid from the grouped walls, I have tried to make it a component and also a group but it still wont let me subtract no matter what i do, I even redrew it and I still can’t get it to unlock and let me subtract the top shape from the walls to create an angle. PLEASE SOMEONE HELP ---
**Author:** ![mihai.s](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/mihai.s/32/202022_2.png) [@mihai.s](https://forums.sketchup.com/u/mihai.s)\ **Post date:** [July 3, 2025, 4:31pm UTC](https://forums.sketchup.com/t/solid-object-subtraction/333486/2 "2025-07-03T16:31:48Z")
Learn the basics of SketchUp at Campus - [learn.sketchup.com](http://learn.sketchup.com), and only then move on to using Solid Tools. ---
**Author:** ![ateliernab](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/ateliernab/32/198399_2.png) [@ateliernab](https://forums.sketchup.com/u/ateliernab)\ **Post date:** [July 3, 2025, 4:37pm UTC](https://forums.sketchup.com/t/solid-object-subtraction/333486/3 "2025-07-03T16:37:47Z")
well, this is just a screenshot of an error message, you’re not giving us much to help you. From what I gather, I’d say that one or more of the selected objects is either not a solid, or is locked. The aforementioned object will be de-selected before sketchup’s solid tool operation is performed. without looking at the sketchup file, it’s the extent of my knowledge… ---
**Author:** ![bmike](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/bmike/32/225451_2.png) [@bmike](https://forums.sketchup.com/u/bmike)\ **Post date:** [July 3, 2025, 4:39pm UTC](https://forums.sketchup.com/t/solid-object-subtraction/333486/4 "2025-07-03T16:39:36Z")
I would take @mihai.s advice and learn the basics… But it seems a lot of users here like to just push onward and brute force their work… if that is how you wanna roll then we’ll need more information to help you - you could post the model, which would be super helpful. Otherwise: ![IMG_5031](https://global.discourse-cdn.com/sketchup/original/3X/8/c/8c3bb8429768b988feab1ee764ddf5b6874037e5.jpeg) ---
**Author:** ![slbaumgartner](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/slbaumgartner/32/7302_2.png) [@slbaumgartner](https://forums.sketchup.com/u/slbaumgartner)\ **Post date:** [July 3, 2025, 5:36pm UTC](https://forums.sketchup.com/t/solid-object-subtraction/333486/6 "2025-07-03T17:36:32Z")
It’s a reference to a skit that Johnny Carson used to do on the Tonight Show. He called his character Karnak and gave joke answers to absurd questions on cards like he is holding in the picture. ---
**Author:** ![bmike](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/bmike/32/225451_2.png) [@bmike](https://forums.sketchup.com/u/bmike)\ **Post date:** [July 3, 2025, 5:50pm UTC](https://forums.sketchup.com/t/solid-object-subtraction/333486/7 "2025-07-03T17:50:17Z")
> Off Topic Warning It will be my go to reply when someone doesn’t include a model or detailed screen shots. @slbaumgartner already explains the reference: [![](https://global.discourse-cdn.com/sketchup/original/3X/e/f/ef6b16342e25778d1371f7cdf9322042dfcad05f.jpeg "Carnac The Magnificent Final Appearance on The Tonight Show") ](https://www.youtube.com/watch?v=NZfhupyncls) ---
**Author:** ![bmike](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/bmike/32/225451_2.png) [@bmike](https://forums.sketchup.com/u/bmike)\ **Post date:** [July 3, 2025, 6:05pm UTC](https://forums.sketchup.com/t/solid-object-subtraction/333486/9 "2025-07-03T18:05:23Z")
> [@dezmo](#): > > Thank you. It doesn’t seem funny or understandable either. And I don’t feel like I should know about this John Carson. There’s a question above, from the OP, but we don’t really know what is going on, so we can guess, pretend to be fortune tellers, or just make stuff up. It’s a dated American thing, Carnac might not be well know around the world. But I thought the image was self explanatory. ---
**Author:** ![RLGL](https://sea2.discourse-cdn.com/sketchup/user_avatar/forums.sketchup.com/rlgl/32/44295_2.png) [@RLGL](https://forums.sketchup.com/u/RLGL)\ **Post date:** [July 3, 2025, 7:15pm UTC](https://forums.sketchup.com/t/solid-object-subtraction/333486/11 "2025-07-03T19:15:51Z")
> [@dezmo](#): > > And I don’t feel like I should know about this John Carson. For what it is worth, he had a very popular late night TV show here in the US.years ago