Note 2 - Significant Accounting Policies (Details Textual) - USD ($)
12 Months Ended
Sep. 07, 2021
Mar. 31, 2022
Mar. 31, 2021
Cash, Uninsured Amount   $ 887,000  
Accounts Receivable, Allowance for Credit Loss, Ending Balance   925,000 $ 300,000
Contract with Customer, Liability, Revenue Recognized     179,000
Advertising Expense   27,546 34,473
Shipping and Handling Costs   9,371 4,264
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total   $ 0 $ 0
Earnings Per Share, Basic, Total (in dollars per share)   $ (0.02) $ (0.01)
Gain (Loss) on Extinguishment of Debt, Total   $ 693,817 $ 0
Paycheck Protection Program CARES Act [Member]      
Gain (Loss) on Extinguishment of Debt, Total $ 361,275 693,817  
Maximum [Member]      
Product Warranty Expense   $ 2,000 $ 2,000
Property, Plant and Equipment, Useful Life (Year)   7 years  
Minimum [Member]      
Property, Plant and Equipment, Useful Life (Year)   5 years  
Electronic Products [Member]      
Warranty Term (Day)   90 days  
Electronic Controllers for Spas and Hot Tubs [Member]      
Warranty Term (Day)   5 years