I think you might be surprised Gordon. I don't know much about the subject, but from what I understand, all a risk assessment needs is a list of potential risks, to acknowledge that they actually exist and have been thought about.

So:

Risk: Body parts trapped between levers and object stone or fulcrum
Avoidance: Ensure levers are long enough to keep participants away from danger areas. Arrange 'spotters' to ensure non participants are kept at a safe distance.

Risk: Lever snaps, showering splinters
Avoidance: All participants to wear eye protection

That kind of level should suffice, assuming all potential risks are actually covered. The biggest crime is leaving off obvious risks...