This instructable presents a video of the machine operating and also some general guidelines for building your own machine.
My basic rule of construction has always been, just use what you got.
Not a lot of science here except an interesting observation: the slinky provides a feedback circuit to the motor and so you get an uneven cycle of operation - the machine goes at two speeds depending on where the slinky is in it's cycle. Kind of fun to watch.
If you want to see a couple of really fine examples of some other folks well crafted slinky machines, look here:
Step 1: Frame of the Machine
Step 2: Drive Motor
The motor is battery powered but I use a little adjustable power supply so that I can play with the speed of the machine.
The gearbox is zip tied to another plastic block which is attached to the wood base with wood screws.
Step 3: Drive Shaft
The second photo shows probably the most complex part of the machine. It is simply a paper clamp which has a hole drilled through it to mount it on the wood frame. The paper clamp holds a 3 inch section of fishing pole that the drive shaft pole fits inside of.
I used two nuts to make the paper clamp stand out from the wood a bit.
I also used a couple more screws/bolts to keep the paper clamp from turning when the shaft is moving.
Step 4: Slinky Holder on the Drive Shaft
Use magnets on the bottom of the lid to hold the slinky in place.
The lid is attached to the drive pole or shaft with a couple of bent metal strips. Use whatever is available to attach the shaft to the lid.
Step 5: Slinky Holder on the Other Side
The last photo shows the backside of the machine.
And thats it. Plug in your batteries, put the slinky on the machine and enjoy!