Note 1 - Accounting Policies - Adoption of ASU No. 2014-09, Financial Position Impact (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Accumulated deficit	$ (12,166,358)		$ (12,166,358)		$ (10,407,797)	$ (10,040,229)
Deferred revenue	345,929		345,929		367,568
Net sales to external customers	8,337,045	$ 9,069,323	26,800,025	$ 31,853,733
Net income (loss)	(542,301)	$ (319,103)	(1,758,560)	$ (314,975)
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Net sales to external customers	8,327,054		26,779,055
Net income (loss)	(552,292)		(1,779,530)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Net sales to external customers	9,991		20,970
Net income (loss)	$ 9,991		$ 20,970
Accounting Standards Update 2014-09 [Member]
Accumulated deficit					(367,568)
Deferred revenue					$ 367,568