3D Printed Shower Caddy Replacement

Challenge: Student wanted to manufacture a replacement piece of a shower caddy/shower storage shelf for his shower at home.  Original piece was broken through use and he wanted to create a replacement.
Background: Student is a senior student (twelve years old) who has worked through our school system.  He has used the 3D Printers and our Laser Cutters for a considerable length of time.  This student has worked on a number of major projects of increasingly difficulty and shown flair and design with his creations.  This replacement part was designed and 3D Printed so it could be replicated exactly to replace the broken part.  It needed to work as part of a larger piece and needed to fit in perfectly with an existing piece.   The 3D Printer was utilized in this example because the part would be exposed to water on a daily basis.    This is the students first attempt at completing the part and the measurements etc were completed independently and designed in Tinkercad. 
Level of Difficulty: High - for a school student context this is about as complicated project that we have seen in the last four years from our students.   Every aspect of this print needs to be correct for it to work in unison with an existing part.   Each of the slots fits into an existing part. 
Timeframe: Nine hours.  The base of the shelf in this design is extremely thin, with a width of 2mm.The intention is for a potential reprint once the print itself once the print is proven to be successful, with that in mind a considerable increase in the print time would be expected by the nature of the base being the most significant feature of the print itself.
Size:   The dimensions of this print is slightly deceptive.   The base measure 140mm across by 120mm the wings at the back of the design are 40mm hight.  As noted in previous description the width of the design is only 2mm thick in places, something to be considered if the project is to be redesigned. 
What we would do differently: This project was created and designed exclusivley without input from the teacher.   The project was to solve an issue at home, where the student had independently identified that a 3D Printer would be the best tool to solve this problem and replace a part that needed to be.   Other than the width of the thickness of the shelf, it is, in our opinion an example of an extremely high calibre.
Next Step for students: With the print complete the student is currently checking its suitability, the only issue of note is ensuring that the slots are accurately aligned with the shower piece and that the width of the shelf is adjusted to take the weight on shower items.