Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net Income	$ 286,842	$ 707,788
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation	336,389	326,520
Gain on disposal of equipment	(5,000)	(300)
Deferred income taxes	24,000	(14,000)
Changes in operating assets and liabilities:
Accounts receivable	(425,167)	(1,427,855)
Inventories	(732,068)	(68,578)
Other current assets	82,154	102,899
Accounts payable	53,396	908,830
Accrued wages and salaries	(18,544)	(14,635)
Other accrued expenses	(236,101)	(67,446)
Unearned revenue and customer deposits	(46,040)	(238,722)
Net cash provided by (used in) operating activities	(680,139)	214,501
Cash flows from investing activities:
Capital expenditures	(906,132)	(225,000)
Proceeds from the sale of equipment	5,000	300
Proceeds from certificates of deposit	3,577,000	1,494,000
Purchases of certificates of deposit	(1,594,000)	(1,245,000)
Net cash provided by investing activities	1,081,868	24,300
Cash flows from financing activities:
Cash dividends paid	(502,389)	(492,727)
Net cash used in financing activities	(502,389)	(492,727)
Net decrease in cash and cash equivalents	(100,660)	(253,926)
Cash and cash equivalents at beginning of period	706,873	1,152,569
Cash and cash equivalents at end of period	606,213	898,643
Supplemental schedule of non-cash investing activities:
Capital expenditures in accounts payable	$ 0	$ 1,427