Note 1 - Accounting Policies - Adoption of ASU No. 2014-09, Financial Position Impact (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Accumulated deficit	$ (11,624,056)		$ (11,624,056)		$ (10,407,797)	$ (10,040,229)
Deferred revenue	356,028		356,028		367,568
Net sales to external customers	8,459,741	$ 10,006,628	18,462,980	$ 22,784,410
Net income (loss)	(977,954)	$ (519,665)	(1,216,259)	$ 4,128
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Net sales to external customers	8,460,954		18,452,001
Net income (loss)	(976,741)		(1,227,238)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Net sales to external customers	(1,213)		10,979
Net income (loss)	$ (1,213)		$ 10,979
Accounting Standards Update 2014-09 [Member]
Accumulated deficit					(367,568)
Deferred revenue					$ 367,568