Note 10 - Segment Reporting - Segment Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Assets	$ 34,784,000	$ 32,007,000	$ 37,912,000
Revenue	8,695,000	4,656,000
Operating (loss) income	(187,000)	(970,000)
Pretax (loss) income	(38,000)	(997,000)
Depreciation and amortization	166,000	251,000
Purchase of property, plant & equipment	146,000	177,000
Intersegment Eliminations [Member]
Assets	25,000	28,000
Revenue	(129,000)	(44,000)
Operating (loss) income	0	0
Pretax (loss) income	0	0
Depreciation and amortization	0	0
Purchase of property, plant & equipment	0	0
Corporate, Non-Segment [Member]
Assets	0	0
Revenue	0	0
Operating (loss) income	(1,037,000)	(706,000)
Pretax (loss) income	(918,000)	(706,000)
Depreciation and amortization	0	0
Purchase of property, plant & equipment	0	0
CVD [Member] | Operating Segments [Member]
Assets	28,509,000	25,312,000
Revenue	5,845,000	2,827,000
Operating (loss) income	138,000	(736,000)
Pretax (loss) income	141,000	(726,000)
Depreciation and amortization	131,000	216,000
Purchase of property, plant & equipment	136,000	145,000
SDC [Member] | Operating Segments [Member]
Assets	4,467,000	4,858,000
Revenue	2,312,000	1,415,000
Operating (loss) income	631,000	442,000
Pretax (loss) income	631,000	442,000
Depreciation and amortization	12,000	13,000
Purchase of property, plant & equipment	10,000	2,000
SDC [Member] | Intersegment Eliminations [Member]
Revenue	129,000	44,000
Materials [Member] | Operating Segments [Member]
Assets		1,809,000
Revenue	667,000	458,000
Operating (loss) income	81,000	30,000
Pretax (loss) income	108,000	(7,000)
Depreciation and amortization	23,000	22,000
Purchase of property, plant & equipment	0	$ 30,000
Materials [Member] | Intersegment Eliminations [Member]
Assets	$ 1,783,000