Note 8 - Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Vacation accrual	$ 3,908	$ 3,814
Allowance for doubtful accounts		734
Reserve for excess and obsolete inventory	152,680	241,624
Business tax credit carryover	30,935
Deferred compensation	17,943	24,451
Net operating loss carryover	5,889,088	5,184,992
Excess of book over tax depreciation	(300,805)	(33,182)
Excess of book over tax work in progress	(847,290)
Valuation allowance	(5,285,222)	(5,422,433)
	(338,763)
Long-term deferred tax asset
Long-term deferred tax liability	(338,763)
	$ (338,763)