Balance Sheets - USD ($)	Mar. 31, 2021	Mar. 31, 2020
Current assets
Cash and cash equivalents	$ 10,427,340	$ 8,065,594
Marketable securities, short-term	7,678,957	19,084,814
Accounts receivable, net of allowance for uncollectible accounts of $15,000	1,964,281	2,694,018
Inventories	3,900,777	3,884,450
Prepaid expenses and other assets	391,278	655,835
Total current assets	24,362,633	34,384,711
Fixed assets
Machinery and equipment	9,254,664	9,280,062
Leasehold improvements	1,810,872	1,797,245
Property, Plant and Equipment, Gross, Ending Balance	11,065,536	11,077,307
Less accumulated depreciation and amortization	10,728,853	10,494,840
Net fixed assets	336,683	582,467
Deferred tax assets	73,538	108,119
Marketable securities, long-term	47,038,669	43,606,495
Right-of-use asset – operating lease	689,216	816,358
Total assets	72,500,739	79,498,150
Current liabilities
Accounts payable	336,591	186,993
Accrued payroll and other	540,474	482,074
Operating lease	150,273	127,134
Total current liabilities	1,027,338	796,201
Operating lease	581,459	706,600
Total liabilities	1,608,797	1,502,801
Shareholders’ equity
Common stock, $0.01 par value, 6,000,000 shares authorized; 4,833,232 issued and outstanding as of March 31, 2021 and 4,835,038 as of March 31, 2020	48,332	48,350
Additional paid-in capital	19,338,127	19,383,956
Accumulated other comprehensive income	1,101,119	516,523
Retained earnings	50,404,364	58,046,520
Total shareholders’ equity	70,891,942	77,995,349
Total liabilities and shareholders’ equity	$ 72,500,739	$ 79,498,150