Note 5 - Property and Equipment - Property and Equipment (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Buildings	$ 493,000	$ 355,000
Machinery and equipment	11,036,000	10,661,000
Office furniture and equipment	1,151,000	1,092,000
Leasehold improvements	507,000	506,000
Software	177,000
	13,364,000	12,614,000
Less accumulated depreciation and amortization	(10,206,000)	(9,968,000)
	$ 3,158,000	$ 2,646,000