Jamie, from my first hand experience with industrial machinery, the state department of Labor and Industry (the dreaded L&I) can help you here. They're more than glad to send out an inspector to look over your shop for safety issues, posted warning signage on machinery etc, etc. As long as you make the inspection request you're not liable for fines for unsafe conditions. If they make an unannounced inspection due to a complaint or whatever that's a different issue. In the State of Washington there are issues to be aware of. Anybody working for payment is automatically covered under state industrial insurance. I assume this would apply to paid demonstrators and possibly class participants. This is where you can get into tricky territory. For instance, if you hire a handy man to do odd jobs around your home you are responsible for their industrial insurance. If they're a professional you can verify online whether premiums are being paid to the state. If they aren't covered (as would likely be the case of an out of state demonstrator) you can sign them up and pay the nominal premiums yourself. If an uninsured individual is hurt on your premises the penalties can be severe. I expect state inspectors will be fairly hard nosed about issues with unguarded, rotating chunks of wood. Probably at a minimum requiring guarding like shown in the attached picture. As a sidenote, the Seattle Woodcraft store typically has at least 10 lathes on display and not a singly one has a guard installed. For sure, bench grinders will need to have full enclosures over the wheels. Even the CBN wheel sellers show their products being used without guarding which has always been surprising to me. The liability insurance company your local club deals with might have some safety guidelines too. Given the litigious society we're in it's no wonder public schools have been forced to give up shop classes. A friend very active in the woodturning community gave up the idea of marketing a clever accessory because the product liability insurance per unit exceeded his projected selling price.