A Sketchup Tip and trick that will save you some time when using section planes in your 3D model. Basically Sketchup is a surface modeller which means the geometry is hollow. When you cut a section through wall or a prism you will see the inside of the geometry that may have supposed to be solid Like this.
Step 2 Ensure your section planes are showing and right click the section cut in Sketchup and select create group from slice.
Note it is easier to place your section in 3D view or perspective instead of parallel projection. Basically this gives your model a 3D perspective as you would see in real life.
Once you have created your group from slice it can be hard to select so here is a TIP hide part of your model by right clicking and select hide. This will make it easier to to select the section group.
Once you select your section group right click and make it a component. Then copy and paste your component in a place where it is easier to work on like in the image shown bellow. You can then simply triple click inside of the copied components and add faces and textures.
When you reactive your section cut you will not see the face as it is still being cut.
There is a plugin that you can use named Skalp you can find it here http://www.skalp4sketchup.com/ it will save you a lot of time, we are talking about integrating Scalp into PlusSpec in the future so stay tuned. the aim is to make your 3d modelling experience seamless.