CONDENSED STATEMENTS OF CASH FLOWS - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 14,598	$ (483,963)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation	395,787	421,412
Amortization	18,615	19,149
Stock based compensation	6,473	11,494
Net gain on sale and disposal of property, plant and equipment		(21,707)
Deferred income taxes	12,839
Changes in working capital components:
Trade receivables	321,347	269,765
Inventories	(385,481)	(290,429)
Prepaid expenses and other assets	(16,184)	215,133
Income tax receivable	(1,365)	(207,854)
Accounts payable	508,323	144,409
Accrued expenses	2,962	(26,896)
Net cash provided by operating activities	877,914	50,513
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property, plant, and equipment	(324,392)	(134,086)
Proceeds from sale of property and equipment		21,707
Purchases of intangible assets	(32,354)	(15,044)
Purchases of short-term investments	(2,920,000)	(1,915,000)
Proceeds on sale of short-term investments	2,895,000	2,266,000
Net cash provided by (used in) investing activities	(381,746)	223,577
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments on long-term debt	(70,040)	(69,564)
Repurchase of common stock		(15,038)
Proceeds from exercise of stock options		1,885
Net cash used in financing activities	(70,040)	(82,717)
NET DECREASE IN CASH AND CASH EQUIVALENTS	426,128	191,373
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	929,700	1,048,713
CASH AND CASH EQUIVALENTS AT END OF PERIOD	1,355,828	1,240,086
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid for interest	36,711	35,776
Cash paid for income taxes, net	$ 7,652	$ 60,003