CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES
Net income	$ 117,000	$ 148,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	567,000	704,000
Amortization of finite-lived intangible assets	75,000	68,000
Gain on disposal of assets		(110,000)
Impairment of note receivable	102,000
Stock-based compensation	88,000	67,000
Bargain purchase gain		(4,000)
Deferred income tax expense (benefit)	41,000	(214,000)
Gain on sale of marketable securities	(21,000)
Dividend from marketable securities	(6,000)	(62,000)
Changes in operating assets and liabilities:
Decrease (increase) in accounts receivable, net	111,000	(890,000)
Increase in inventories, net	(237,000)	(62,000)
Increase in prepaid expenses and other assets	(28,000)	(1,000)
(Decrease) increase in accounts payable, accrued compensation and commissions expense and other accrued liabilities	(128,000)	634,000
Net cash provided by operating activities	681,000	278,000
INVESTING ACTIVITIES
Purchase of marketable securities	(1,002,000)	(2,695,000)
Capital expenditures	(131,000)	(172,000)
Acquisition of a business		(295,000)
Proceeds from sale of land	96,000
Other	34,000	117,000
Net cash used in investing activities	(1,003,000)	(3,045,000)
FINANCING ACTIVITIES
Proceeds from issuance of common stock, net of issuance costs	10,794,000
Purchase of treasury stock		(8,000)
Net cash provided by (used in) financing activities	10,794,000	(8,000)
Increase (decrease) in cash and cash equivalents	10,472,000	(2,775,000)
Cash and cash equivalents at beginning of year	2,778,000	5,553,000
Cash and cash equivalents at end of year	13,250,000	2,778,000
Supplemental Disclosure:
Cash paid for interest	23,000	17,000
Cash paid for income taxes	$ 41,000	52,000
Supplemental Schedule of Noncash Investing Activities:
Fair value of equipment acquired		85,000
Fair value of intangible assets acquired		214,000
Current assets acquired		45,000
Current liabilities assumed		(45,000)
Bargain purchase gain		(4,000)
Cash consideration paid		$ 295,000