26. Now we've modelled all the bosses, we need to extrude them out into the shelled cavity.
Type Q, then select all the bodies you just created, the rectangles and the three circles in the centre (But not the two horizontal rectangles in the centre either side of the middle circular boss), in the extrude tool window, select Extent - To object, select "Object, and click on the edge of the brick, then select from Chain Faces - "Extend faces". This extrudes all the bodies out to the extent of the brick. The video shows all the steps, watch it a few times before you attempt it.
27. Now we need to extrude the central rectangular bosses.
Type Q, select the two central rib/bosses, then type 7mm and press return. Use the view cube to look at your finished underside!
28. Swivel the view around now so you can see the top of the brick. We need to add the Lego writing to the top of your studs (or your name - i don't mind, just keep it to 4 characters).
Use the view cube to rotate the brick and centre it on the top view by clicking "top".
29. Type S, type "Te", select the Text tool. Click on the top left stud to select the face of the stud then click again where you want the text to start.
Use the text tool to change the font to DIN condensed, italicise, then type "LEGO" (Don't do it in lower case like i did!) and switch the angle to 180 degrees so it's the right way up and change the height to 2.2mm. Click ok.
30. Drag the text to the center of the stud, right click it and select explode text - this allows us to treat the text like other sketches and to be able to extrude with it.