By applying what I have learned in engineering class from using tools like the digital calper to gather precise dimensions, and then reconstruct the Arduino itself vaugely in 3D, and then build a case that fits in accordance to the Arduino’s dimensions. Schematics were planned out with 3D printer error, as well as held together with clamps(?) The final product was never printed while in my direct presence, but the schmatics held up when compared to the actual spec sheet.
Additional details are pending, as I have yet to get access to the project files (my AutoDesk Inventor subscription expired!)