I took a piece of PVC pipe from work, drilled a hole in it, and attached a 3 foot long piece of string with a 5lb weight (could be anything you want tied to the end) on it. You then roll up the string and then back down. Seems silly at first but after 3 up and downs you lower arm muscles will be dead. 
It has amused me thus far and I imagine I'll be sore tomorrow.
			
			It has amused me thus far and I imagine I'll be sore tomorrow.
				
		
			