Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities:
Net income	$ 1,544,789	$ 2,525,726
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	68,511	70,025
Net loss (gain) on marketable securities	853,938	(65,527)
Allowance for doubtful accounts	8,146	9,678
Deferred income taxes	(51,319)	149,454
(Increase) decrease in operating assets:
Accounts receivable	(301,337)	(586,995)
Inventories	(317,415)	497,487
Prepaid expenses and other current assets	(54,421)	(33,751)
Prepaid income taxes	(231,405)	15,740
Increase (decrease) in operating liabilities:
Accounts payable	5,548	(5,797)
Accrued expenses	(81,532)	41,268
Deferred revenue	(190,164)
Income taxes payable	(88,738)
Net cash provided by operating activities	1,164,601	2,617,308
Cash flows from investing activities:
Acquisition of property, plant and equipment	(12,293)	(38,758)
Proceeds from sale of marketable securities	1,658,292	1,832,827
Purchase of marketable securities	(1,286,849)	(2,053,744)
Net cash provided by (used in) investing activities	359,150	(259,675)
Cash flows from financing activities:
Dividends paid	(1,699,392)	(2,204,616)
Net cash used in financing activities	(1,699,392)	(2,204,616)
Net (decrease) increase in cash and cash equivalents	(175,641)	153,017
Cash and cash equivalents at beginning of period	531,213	591,444
Cash and cash equivalents at end of period	355,572	744,461
Supplemental disclosure of cash flow information
Taxes paid	350.000	300,000
Dividend Declared [Member]
Supplemental disclosure of cash flow information
Supplemental disclosure of non-cash dividends payable	$ 507	$ 657