Note 1 - Accounting Policies - Summary of Geographic Area Data (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net sales to external customers
Net sales to external customers		$ 8,337,045	$ 9,069,323	$ 26,800,025	$ 31,853,733
UNITED STATES
Net sales to external customers
Net sales to external customers		6,498,778	7,082,540	20,505,226	24,791,337
Australia, New Zealand [Member]
Net sales to external customers
Net sales to external customers		155,663	224,419	565,126	710,877
CANADA
Net sales to external customers
Net sales to external customers		153,189	199,877	556,866	681,265
MEXICO
Net sales to external customers
Net sales to external customers		127,859	105,021	347,641	351,559
Europe [Member]
Net sales to external customers
Net sales to external customers	[1]	807,097	890,783	3,002,528	3,398,941
Asia [Member]
Net sales to external customers
Net sales to external customers	[2]	$ 594,459	$ 566,683	$ 1,822,638	$ 1,919,754

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

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