You would think you could make a shape and push/pull it to make a hole, but the method outlined below is more foolproof.



Making Holes
  1. Open SketchUp


  2. Create a base:



  3. Select the Circle tool (C) and create a circle



  4. Select the Push/Pull tool (P) and extrude the circle up



  5. Select the spacebar to choose the Select tool and triple click the cylinder



  6. CTRL+click on the cylinder and select Make Group from the Context Menu:



  7. CTRL+click on the group and select Align Group/Component from the Context Menu:



  8. Click where you want the origin point to be:



  9. Click where you want the end of the X axis:



  10. Click where you want the end of the Y axis:


  11. The popup will appear. Click on No to move the cylinder to the selected spot:



  12. Select the Move tool (M)



  13. Hold the up arrow while dragging the cylinder down:



  14. CTRL+click on the cylinder and select Explode from the Context Menu



  15. Select the Select tool (spacebar) and select both entities:



  16. CTRL+click and select Intersect Faces>With Selection from the Context Menu:



  17. Delete and delete all parts of the cylinder:
            


  18. Select the interior of the hole with the Selection tool (spacebar) and CTRL+click on the selection and choose Reverse Faces from the Context Menu:



  19. Et, viola, you have a hole
    .




Now what?

  1. Create a model with some holes.