Materials Needed:

3/8" - 1/2" thick clear Plexiglass/Acrylic, cut to 3"x6"
1 Small Slinky (SLinky Jr. ~1.75" O.D.), cut to ~30.5 - 36.5 loops **It is important to cut to the 1/2 loop for proper assembly
2 Pieces 14 AWG bare solid copper wire, cut to ~2.5" length
2 12 AWG metal crimps (Crimp-on ring terminals with the ring cut off)
2 Binding posts, with the bottom lead cut off (so it doesn't stick out the bottom of the baseboard)
Overhead projector
Power supply and leads capable of delivering 15 - 20 Amps

Approximate Building Materials Cost:

$9.00

Tools Needed:

Radial saw (only to cut the base)
Sander (for sanding only the edges of the base)
Drill press with various drill bits
2 Needle-nose pliers
Crimper

Assembly Instructions:

1. Cut the base and sand only the edges and corners (the faces need to be clear for the overhead projector).
2. Drill two holes in the base as diagrammed, 1/2" from the ends and .65" from alternating sides. Our binding post had a base post diameter of .305" so we drilled the holes at 19/64", or .297". Depending on the diameter of your binding post, drill the hole slightly smaller so that the post will fit into the hole tightly and not move. Cut the bottom of the post off so that it doesn't stick out the bottom of the baseboard. You can also countersink around the hole on the bottom of the baseboard so that you can use the binding post's nut to secure it to the board. Push the binding posts through the baseboard so that the wire holes in the posts are parallel to the long sides of the baseboard.
3. Using pliers, bend the two ends of the slinky so that the slinky lays flat and the ends are horizontal and also laying flat against the baseboard, but on opposite sides of the slinky's diameter. The ends of the slinky should line up with wire holes in the binding posts.
4. Crimp the copper wires and each end of the slinky with a metal crimp, so that the wire is attached away from the slinky. Bend the wire as diagrammed so that it will pass through the wire hole in the binding post. Feed the copper wire through the binding posts. You might have to do some additional wire bending and positioning to get them to fit properly through the binding posts. Using needle-nose pliers, bend the ends of the copper wires into a loop as shown. This will keep the wires from snagging and will make it easier for you to adjust them.
** The copper leads are there so that you can adjust the stretch of the slinky to get the desired effect. As you move the leads in and out of the binding posts you may need to twist the leads a bit to keep the slinky properly aligned.
5. Put it on the overhead and get your power supply ready. THE SLINKY WILL HEAT UP VERY QUICKLY!! Only close the circuit momentarily, for about a second each time. You should be able to repeat the demonstration 5 or 6 times in succession before it gets too hot.

Operating Specifications:

Slinky resistance ~= 0.044 Ohms/loop
Current necessary for effect 15 - 20 Amps