6. Segment Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Net Sales:
Customer sales	$ 38,966,000	$ 38,456,000
Intercompany sales	0	0
Total Net Sales	38,966,000	38,456,000
Share based compensation	131,000	170,000
Depreciation	2,774,000	2,561,000
Interest (income) expense	112,000	177,000
Income tax (benefit) expense	(314,000)	107,000
Location profit (loss)	(1,136,000)	444,000
Capital expenditures	3,099,000	1,203,000
Location long-lived assets	18,389,000	15,907,000
Location assets	36,329,000	35,729,000
Inter-Company Eliminations [Member]
Net Sales:
Customer sales	0	0
Intercompany sales	(7,088,000)	(11,990,000)
Total Net Sales	(7,088,000)	(11,990,000)
Share based compensation	0	0
Depreciation	0	0
Interest (income) expense	0	0
Income tax (benefit) expense	10,000	(9,000)
Location profit (loss)	19,000	(10,000)
Capital expenditures	0	0
Location long-lived assets	0	0
Location assets	(2,508,000)	(714,000)
United States (Corpus Christi) [Member]
Net Sales:
Customer sales	23,998,000	26,678,000
Intercompany sales	38,000	98,000
Total Net Sales	24,036,000	26,776,000
Share based compensation	131,000	170,000
Depreciation	1,119,000	1,076,000
Interest (income) expense	(2,000)	(2,000)
Income tax (benefit) expense	(104,000)	(131,000)
Location profit (loss)	(604,000)	(406,000)
Capital expenditures	1,062,000	463,000
Location long-lived assets	5,437,000	5,291,000
Location assets	16,822,000	17,013,000
European (TPT) [Member]
Net Sales:
Customer sales	11,125,000	9,313,000
Intercompany sales	3,817,000	7,357,000
Total Net Sales	14,942,000	16,670,000
Share based compensation	0	0
Depreciation	1,521,000	1,343,000
Interest (income) expense	96,000	107,000
Income tax (benefit) expense	(218,000)	247,000
Location profit (loss)	(882,000)	826,000
Capital expenditures	1,975,000	735,000
Location long-lived assets	12,181,000	9,832,000
Location assets	15,608,000	13,417,000
Asian (TMM) [Member]
Net Sales:
Customer sales	3,843,000	2,465,000
Intercompany sales	3,233,000	4,535,000
Total Net Sales	7,076,000	7,000,000
Share based compensation	0	0
Depreciation	134,000	142,000
Interest (income) expense	18,000	72,000
Income tax (benefit) expense	(2,000)	0
Location profit (loss)	331,000	34,000
Capital expenditures	62,000	5,000
Location long-lived assets	771,000	784,000
Location assets	$ 6,407,000	$ 6,013,000