This is one of the props built for our annual Halloween party. It is part of a larger project, but could easily act as it's own piece for your event.
It was designed to act as a photo opportunity, so the dull "blade" is completely stationary and the lunette (the head hole) is large enough for most people to slip their head in and out of without lifting the top.
The Instructable for the executioner to go along with it can be found here.
Step 1: Gathering your materials and tools
5 8ft length of 2x4 (cheap wall stubs work great)(*)
1 8ft length of 2x10
1 sheet of dark hardboard paneling (a sheet at least 3 ft X 2 ft)
2 screw eyes
Some rope (10-12 ft should be enough)
4 bolts that are 2 inches in length (with matching washers and nuts)
A large hinge that will mount onto the side of 2 of the boards
Wood or deck screws (2.5 inch worked well for me)
Silver metallic spray paint (matte finish)
Dark wood stain
(You can skip one of the 2x4 if you use the alternate cut in step 2.)
For the tools, your basic requirements are to cut your studs to the right length and then cut 2 circular sections in your 2x10. You can use whatever saw you have available, but lacking access to a band saw I found it easiest to make the straight cuts with a circular saw and the round cut with a jig saw.
Jig Saw (Band saw would be better to cut the thicker pieces, but use whatever tools you have to cut a circle)
Power Drill (with drill and screwdriver bits)
Something to assist in drawing a circle. (Paint can, or plate work fine.)
Paint brush and paper towels