Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Total	$ 0	$ 0	$ 0
Provision for Doubtful Accounts	0	0	0
Allowance for Doubtful Accounts Receivable, Write-offs	$ 0	0	0
Product Warranty Term	1 year
Impairment of Long-Lived Assets Held-for-use	$ 0	0	0
Depreciation, Depletion and Amortization, Nonproduction, Total	692,665	798,300	850,970
Cost of Revenue, Total	6,274,744	$ 6,078,294	$ 6,616,852
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		4,000	6,000
Shipping and Handling [Member]
Cost of Revenue, Total	$ 8,420	$ 12,760	$ 20,721
Machinery and Equipment [Member]
Property, Plant and Equipment, Useful Life	5 years
Leasehold Improvements [Member]
Property, Plant and Equipment, Useful Life	5 years