3D Printed Tractor Pencil Sharpener

Above: Design shown prior to removal of rafting

Challenge: To incorporate a pencil sharpener into a 3D Printed design.
Background: This challenge came as part of a group of objects supplied to students.   They were given a group of common objects from the classroom - pencil sharpeners and magnets.   There were several other groups of students operating in a process which involved a design/plan on paper and then was followed by a digital creation and feedback.  Other groups of students settled on a Pacman design (as featured on this blog here) and there are other designs to come.   These students opted for a tractor design with the design of the tractor coming from the main Tinkercad interface as the tractor was built from the basic shapes (starting with a rectangle for the base).   The students then added additional features to the tractor and produced the print shown.   Key to this was reviewing the print prior to printing to ensure that it was balanced, as in a review it was shown that the wheels needed to be adjusted.  This was two students who are ten years old first independent and significant 3D Printing project.   It should also be noted

Above: Design showing location of pencil sharpener.

that the students had minimal rafting on the design with the supportive PLA being restricted to the amount that was underneath the base of the tractor.   The students are going to review the print when it is completed and look to add additional details to the tractor.  These are going to be printed in relation to the size of the tractor that has been produced (see below).
Level of Difficulty: High - this design needs to work on two levels, the first aspect is the tractor design and creation.   The second aspect was the location of the pencil sharpener.  The students opted to have a inbuilt part of the tractor that was located at the front with an insert on the front right for the waste created by the pencil sharpener.  Both thsee aspects needed to work in unison for the print to be successful.  The pencil sharpener was a mass produced inexpensive plastic one which allowed the possibility of it being super glued into place or being slightly adapted to fit a specific place with regards to the print.

Time frame: Sixteen hours - given the scope and size of the print this is the minimum that would be required to make this print both robust and successful.
Size: The print was 140mm long and 130mm high including the wheels.   The base of the tractor was 40mm across.  The location hollow for the pencil sharpen was essentially a 30mm by 30mm insert into the base of the tractor. 
What we would do differently: Very little - two students have worked on a design for a considerable amount of time to rework, revise and produce something significant.