Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net Income	$ 56,568	$ 286,842
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation	337,356	336,389
Gain on disposal of equipment	0	(5,000)
Deferred income taxes	(24,000)	24,000
Changes in operating assets and liabilities:
Accounts receivable	(894,369)	(425,167)
Inventories	(227,204)	(732,068)
Other current assets and prepaid income taxes	(225)	82,154
Accounts payable	437,728	53,396
Accrued wages and salaries	(15,892)	(18,544)
Other accrued expenses	(115,663)	(236,101)
Unearned revenue and customer deposits	(44,338)	(46,040)
Net cash used in operating activities	(490,039)	(680,139)
Cash flows from investing activities:
Capital expenditures	(166,667)	(906,132)
Proceeds from the sale of equipment	0	5,000
Proceeds from certificates of deposit	2,241,000	3,577,000
Purchases of certificates of deposit	(1,743,000)	(1,594,000)
Net cash provided by investing activities	331,333	1,081,868
Cash flows from financing activities:
Cash dividends paid	(212,549)	(502,389)
Net cash used in financing activities	(212,549)	(502,389)
Net decrease in cash and cash equivalents	(371,255)	(100,660)
Cash and cash equivalents at beginning of period	1,429,454	706,873
Cash and cash equivalents at end of period	1,058,199	606,213
Supplemental schedule of non-cash investing activities:
Capital expenditures in accounts payable	$ 1,330	$ 0