Over the years, one tool that has come to the fore is moulaging patients with simulated injuries. This can make for a much more realistic exercise and I think the visual element is critically important for volunteers who have perhaps not dealt with significant trauma injuries in the past in real life.
I've seen people with moulage wounds that include bars of metal sticking out of them, etc. When you go beyond the application of latex wounds to using make-up and theater-style artistry, it can look very realistic.
Recently I came across the company Moulage Concepts, which is located in California. You can hire them to do the moulage for an exercise, or they also sell moulage kits, which is something I had not been aware of previously. Doesn't everyone need a simulated "perforated bowel" in their inventory of injuries?
Lastly, they also offer training. You can have the best kit in the world, but if you don't know how to use it properly, what good does it do for you.