Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net Income	$ 540,128	$ 56,568
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation	330,165	337,356
Loss on disposal of equipment	16,081	0
Deferred income taxes	(31,000)	(24,000)
Changes in operating assets and liabilities:
Accounts receivable	(1,706,441)	(894,369)
Inventories	(1,158,666)	(227,204)
Other current assets	84,901	(225)
Accounts payable	668,880	437,728
Accrued wages and salaries	204,563	(15,892)
Other accrued expenses	189,160	(115,663)
Unearned revenue and customer deposits	(43,724)	(44,338)
Net cash used in operating activities	(905,953)	(490,039)
Cash flows from investing activities:
Capital expenditures	(116,463)	(166,667)
Proceeds from certificates of deposit	1,743,000	2,241,000
Purchases of certificates of deposit	0	(1,743,000)
Net cash provided by investing activities	1,626,537	331,333
Cash flows from financing activities:
Cash dividends paid	(212,549)	(212,549)
Net cash used in financing activities	(212,549)	(212,549)
Net increase (decrease) in cash and cash equivalents	508,035	(371,255)
Cash and cash equivalents at beginning of period	2,567,731	1,429,454
Cash and cash equivalents at end of period	3,075,766	1,058,199
Supplemental schedule of non-cash investing activities:
Capital expenditures in accounts payable	$ 0	$ 1,330