First, anytime you use real cutlery in a scene, you must be careful in handling it as not to injure or kill someone. It's hard to have repeat customers if you kill them.
If you use some of the plastic weapons that are on the market be sure to try to authenticate them by dirtying them up a bit. Some dried blood, dirt, grease, this sort of thing and you're in business. Even if they are plastic they are still capable of poking some-one's eye out (actually you can't poke someone's eye out, but you can poke it in). Anyway, here are some ideas of how to take ordinary knives and weapons and alter them to where they look like they've done some damage, or are doing some damage.
First, there is a machete with a section cut out of it to fit over your arm. It makes it look like your arm is in the process of being severed. The cleaver has a similar section cut out, except this one is for the head. You can attach a leather strap to it and harness it to your head. Then comb your hair over the strap, instant head wound.
The third weapon is a kitchen knife, dulled down, with a rubber bulb attached to a tube fixed to one side. This bulb is filled with blood, and when you run it across the arm or whatever, squeeze the bulb and bleed. The tube can be attached to the knife with tape or a hot glue gun
The chainsaw is probably the most identifiable tool with horror movies. We used it in the Butcher Shop scene, as well as the Friday 13th scene. The noise is easily recognizable, so the people are afraid even if they don't see it. We used the chainsaw only after taking the chain off it. This makes it safe, and it must never be used with the chain intact. If you want, you can tape small pieces of chrome mylar to the back of the chainsaw to look like blades. The vibration of the saw causes them to shimmer as if they're moving along the blade. Another alternative is to have the noise on a tape, but it's not as effective.
I want to state unequivocally that I don't recommend using nooses for hanging scenes as they are always dangerous. On the other hand I feel it is my duty to give you safe, harmless alternatives, and safety tips on this. First, a noose should be constructed as shown to the left. The ropes should run under the arms, and under the arms only. There should never be any thing around the neck connected to the rope itself. The piece of rope that wraps around the neck is separate and connects around the neck with velcro or snaps. This should never be even wrapped around the noose rope at all. Also, never jump off any platform or chair while wearing this thing. You can possibly pull your arms out of socket. If you need this effect, I suggest using a mannequin, or have a harness made that fits around the whole chest that connects to the rope. Be Careful!
The above "How-To" is an excerpt from Tim Harkleroad's "The Complete Haunted House Book" for more information about this and other great haunted house reference books go to MoonLighting Publication's website "Haunted House Books On-Line" at www.hauntedhousebooks.com. You can e-mail Tim at moonpub@aol.com