Teaching Tip: Designing Three-Dimensional (3-D) Printed Struvite and Calcium Oxalate Crystals for Microscopic Examination.

Accredited colleges of veterinary medicine are required by the American Veterinary Medical Association (AVMA) Council on Education (COE) to provide learners with hands-on diagnostic method training, including urinalysis. Although teaching hospitals and affiliated clinical partners offer opportunities to test and interpret urine, caseload is unpredictable. Textbook images and published case reports offer substitutes for experiential learning. However, these read-only modalities lack experiences for learners to evaluate slides microscopically for crystalluria. This teaching tip describes the development of three-dimensional (3-D) printed struvite and calcium oxalate models for skills training. Micro-precision 3-D printed models were designed using computer-aided design (CAD) software. Geometric representations in the Standard for the Exchange of Product Data (STEP) file format were exported for 3-D printing on 2 µm resolution platforms. Prints were manufactured from high temperature laminating (HTL) resin and affixed to glass slides. Although these 3-D prints are macroscopic rather than microscopic, their orientation on a fixed template side by side allows learners to differentiate between shapes, a skill that is key to urine sediment examination. These proof-of-concept prototypes will be integrated into the author's pre-clinical curriculum so that learners can gain experience identifying and differentiating between printed struvite, calcium oxalate monohydrate, and calcium oxalate dihydrate models as they would during routine inspection of urine. Formal feedback on the efficacy of these printed models will be solicited from learners and the instructional team. Future iterations will miniaturize the printed models to reflect their real-to-life microscopic dimensions more accurately.