Note 10 - Concentration of Credit Risk - Concentration of Credit Risk, Net Sales (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net Sales	$ 8,329,043	$ 10,128,436	$ 30,297,835	$ 36,508,220
Customer One [Member]
Net Sales	$ 1,799,000	$ 2,395,000	$ 8,136,000	$ 9,738,000
Customer One [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Percent of net sales	22.00%	24.00%	27.00%	27.00%
Customer Two [Member]
Net Sales	$ 1,559,000	$ 2,686,000	$ 8,424,000	$ 10,796,000
Customer Two [Member] | Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Percent of net sales	19.00%	27.00%	28.00%	30.00%