We are nearly done. We are going to add some style to your cube by adding some FILLETS or CHAMFERS.
What is a FILLET: A fillet or round connects two objects with a tangent arc in 2D, or creates a rounded transition between the adjacent faces of a 3D solid. An inside corner is called a fillet and an outside corner is called a round; you can create both using the FILLET command.
What is a CHAMFER: The chamfer tool creates a beveled feature on selected edges, faces, or a vertex.
From the MAIN TOOLBAR select modify then FILLET or CHAMFER
After you have selected FILLER or CHAMFER select the edge that you wish to apply the change too.
Repeat this with any other edge you wish to add a FILLER or CHAMFER to.
CONGRATS you have completed your cube within a cube!!
Now will save your file so it can be 3D Printed!
From the MAIN TOOLBAR select the MAIN MENU drop-down arrow
Then select SAVE and TO MY COMPUTER
Name your file using the following format CUBE_IN_CUBE_YOURNAME