Note 12 - Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Inventories	$ 145,844	$ 116,673
Bad debts	8,773	13,799
Accrued liabilities	281,475	140,280
Prepaid expense	(95,371)	(59,085)
Depreciation and amortization	2,928,232
Depreciation and amortization		166,798
Research and development and other credit carryforwards	1,266,043	2,150,820
Net operating loss carryforward		59,852
Directors stock option plan	62,134	27,074
Total deferred tax asset (liability)	(1,259,334)
Total deferred tax asset (liability)		2,616,211
Valuation allowance	(47,319)	(47,319)
Reserve for uncertain tax positions	(395,000)	(395,000)
Total reserves & allowances	(442,319)	(442,319)
Net deferred tax asset (liability)	(1,701,653)
Net deferred tax asset (liability)		$ (2,173,892)