From access to confidence: Closing the 3D printing self-efficacy gap with a brief mandatory exercise

Additive manufacturing (AM) competence is increasingly expected of mechanical engineering graduates, but AM training comparable to that of traditional manufacturing tools can seem difficult to fit into existing coursework. Printer access alone leaves students roughly one Likert point less confident in operating and producing parts with fused filament fabrication (FFF) printers than with the traditionally taught tools of mills, lathes, and computer-aided design (CAD). This five-semester study tests whether a deliberately minimal mandatory exercise, where students individually slice, transfer, and print one part within an existing laboratory session (∼15 min; under US$4 per student including hardware), closes that gap. In the mandatory-exercise semester (n = 85), post-semester FFF self-efficacy was statistically equivalent to mill, lathe, and CAD within ±0.5 points (Holm-adjusted equivalence p < .002). Low FFF self-efficacy fell from 17–22% under access alone to 1.2% (p < .001), and team-level FFF non-use fell from 21% to 5% (p = .03). When the exercise was made optional (n = 107; estimated completion below 20%) while all other changes retained, the gap re-emerged (10–11% low self-efficacy; equivalence rejected throughout), supporting, though not confirming, that a mandatory exercise closes the gap. A brief mandatory, individual FFF exercise is thus a low-cost, high-value addition to design and manufacturing coursework.