How Do I make my object a solid and Get a volume calculation? So that I can 3d print my object?

Module #3 Advanced 3D Print.skp (238.7 KB)

Remove the excess geometry in the cylinder component. Shown in red at the corner of the bounding box.

You don’t need the top level group. Once the cylinder components are fixed, the central group and the four components will be solid. Most slicers will be able to handle the .stl file from there. If yours won’t, explode all, intersect the geometry and erase the internal stuff.

By the way, your profile is confusing it says you are using SketchUp for Schools (which is evident in your model) but it also says you are using Pro.

Sorry I am new to this app how do I remove the excess geometry in the Cylinder?

Open the component for editing (double click on it with the Select tool. Then use the Eraser to erase that geometry.

Module #3 Advanced 3D Print (2).skp (187.6 KB)
Where is the geometry on the module?

I didn’t tell you to delete the geometry of the cylinders. You need to delete the little rectangle at the corner of the bounding box.

Go back to the previous version of the file. Open one of the cylinder components for editing and erase that unneeded rectangle.

I deleted the little rectangles what do I do now?
Module #3 Advanced 3D Print (3).skp (197.3 KB)

Again, I didn’t tell you to explode the cylinder components. Please do what I said to do at the beginning. Explode the top level group only. This will leave you with the central group and the four cylinder components. Open one of the cylinder components for editing and erase the tiny rectangle. Since the cylinder is in a component, editing the one component will remove the rectangle from the other copies as well. Then click outside of the component to exit Edit mode. This will leave you with a solid group in the middle and four solid components. You should then be able to export the .stl file and send it to the slicer for printing.