Step 1: Supplies
A Chain about 3ft Long.
2 Hose Claps
and a Weight (Circle Bar or Dumbbell)
Step 2: Put Together
Then loop the small end of the hose clamp through one end of the chain and then put it around the bar in the middle and tighten it down.
Step 3: Put Together Pt. 2
And your done.
Step 4: Using It.
Do that non-stop until the weight is at the bar with the chain wrapped around it and then with you arms still out do the same thing but backwards un-wrapping the chain until it is completely off the bar.
This should give your forearms a good workout.
NOTE: This is a very hard workout so only do what you can. It can severely hurt your arms. Be Safe!