Note 1 - Accounting Policies - Summary of Geographic Area Data (Details) - USD ($)		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net sales to external customers
Net sales to external customers		$ 8,459,741	$ 10,006,628	$ 18,462,980	$ 22,784,410
UNITED STATES
Net sales to external customers
Net sales to external customers		6,336,387	7,449,858	14,006,448	17,708,797
Australia, New Zealand [Member]
Net sales to external customers
Net sales to external customers		177,536	227,032	409,464	486,458
CANADA
Net sales to external customers
Net sales to external customers		161,557	217,085	403,677	481,388
MEXICO
Net sales to external customers
Net sales to external customers		112,411	89,221	219,782	246,538
Europe [Member]
Net sales to external customers
Net sales to external customers	[1]	1,030,546	1,307,383	2,195,430	2,508,158
Asia [Member]
Net sales to external customers
Net sales to external customers	[2]	$ 641,304	$ 716,049	$ 1,228,179	$ 1,353,071

[1] Europe consists of United Kingdom, Ireland, France, Germany, Austria, and the Netherlands.

[2] Asia consists of Philippines, Malaysia, Singapore, and Indonesia.