Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net income	$ 1,442,116	$ 1,033,434
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	607,477	627,475
Loss from disposal of equipment	318	3,719
Deferred income taxes	(15,000)	(38,000)
Changes in operating assets and liabilities:
Accounts receivable	(840,290)	(236,992)
Inventories	(452,996)	151,945
Other current assets	337,461	63,541
Accounts payable	469,508	230,949
Accrued wages and salaries	281,228	284,720
Other accrued expenses	4,555	(134,562)
Unearned revenue and customer deposits	(203,457)	104,962
Net cash provided by operating activities	1,630,920	2,091,191
Cash flows from investing activities:
Capital expenditures	(936,111)	(868,605)
Proceeds from the sale of equipment	1,022	0
Proceeds from certificates of deposit	2,988,000	4,813,000
Purchases of certificates of deposit	(2,988,000)	(4,075,000)
Net cash used in investing activities	(935,089)	(130,605)
Cash flows from financing activities:
Cash dividends paid	(589,341)	(589,341)
Net cash used in financing activities	(589,341)	(589,341)
Net increase in cash and cash equivalents	106,490	1,371,245
Cash and cash equivalents at beginning of period	800,894	231,252
Cash and cash equivalents at end of period	907,384	1,602,497
Supplemental schedule of non-cash investing activities:
Capital expenditures in accounts payable	$ 2,585	$ 18,250