Fig. 1

a A surgeon simulating a complex congenital heart surgical procedure on a 3D-printed heart model at the hands-on surgical training (HOST) course. b A congenital heart surgeon demonstrating the arterial switch operation on a 3D-printed heart model at the HOST course. Note that the models are stuck to the table at a fixed height forcing the surgeon to sit down preventing them from using their surgical loupes. A simple headlight is used to illuminate the model. The procedure is video recorded for retrospective assessment (not shown)