go to the rectangle tool and form a base.
Step 1: Lift
use the transform tool to lift up the base.
select the base with the pen tool and lift it
you should have a 3d rectangle a this point.
go to the protractor and make 2 90 degree angles to make an arrow.
make sure the angles are = in length.
square up both ends of your design
select the 3d text tool on the tool tab and place it on the side of your design
export it over to 123d make, make it an interlocking dxf, then you will be ready to print.