Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income (loss)	$ 859,635	$ (722,948)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation	660,489	676,137
Loss on disposal of equipment	16,081	0
Deferred income taxes	(72,000)	(49,000)
Changes in operating assets and liabilities:
Accounts receivable	(746,528)	1,051,677
Inventories	(1,903,375)	205,391
Other current assets and prepaid income taxes	64,595	(292,587)
Accounts payable	576,083	(145,401)
Accrued wages and salaries	394,494	119,541
Other accrued expenses	19,635	(126,864)
Unearned revenue and customer deposits	(169,245)	(73,023)
Net cash provided by (used in) operating activities	(300,136)	642,923
Cash flows from investing activities:
Capital expenditures	(345,213)	(255,352)
Proceeds from certificates of deposit	3,337,000	3,486,000
Purchases of certificates of deposit	(598,000)	(3,735,000)
Net cash provided by (used in) investing activities	2,393,787	(504,352)
Cash flows from financing activities:
Cash dividends paid	(425,098)	(309,161)
Net cash used in financing activities	(425,098)	(309,161)
Net increase (decrease) in cash and cash equivalents	1,668,553	(170,590)
Cash and cash equivalents at beginning of period	2,567,731	1,429,454
Cash and cash equivalents at end of period	$ 4,236,284	$ 1,258,864