Business Segments - Summary of company's operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	$ 11,168	$ 9,060
Costs of goods sold, inclusive of depreciation	(8,530)	(8,067)
Gross margin	2,638	993
Operating expenses:
Selling, general and administrative	(2,182)	(1,973)
Operating income/(loss)	456	(980)
Other income/(expense):
Other income: employee retention credit (ERC)		1,730
Interest expense	(70)	(61)
Gain on sale of equipment	26
Total other (expense)/income, net	(44)	1,669
Income (loss) before income tax provision	412	689
Income tax provision (benefit)	87	148
Net income/(loss)	325	541
Capital expenditures, net	115	14
Operating Segments
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	11,168	9,060
Costs of goods sold, inclusive of depreciation	(8,530)	(8,067)
Gross margin	$ 2,638	$ 993
Gross margin %	23.60%	11.00%
Operating expenses:
Selling, general and administrative	$ (2,182)	$ (1,973)
Total operating expenses	10,712	10,040
Operating income/(loss)	456	(980)
Other income/(expense):
Other income: employee retention credit (ERC)		1,730
Interest expense	(70)	(61)
Gain on sale of equipment	26
Total other (expense)/income, net	(44)	1,669
Income (loss) before income tax provision	412	689
Income tax provision (benefit)	87	148
Net income/(loss)	325	541
Capital expenditures, net	77	14
Operating Segments | ATG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	9,168	7,223
Costs of goods sold, inclusive of depreciation	(6,815)	(6,210)
Gross margin	$ 2,353	$ 1,013
Gross margin %	25.70%	14.00%
Operating expenses:
Selling, general and administrative	$ (1,774)	$ (1,585)
Total operating expenses	8,589	7,795
Operating income/(loss)	579	(572)
Other income/(expense):
Other income: employee retention credit (ERC)		1,413
Interest expense	(70)	(60)
Gain on sale of equipment	26
Total other (expense)/income, net	(44)	1,353
Income (loss) before income tax provision	535	781
Income tax provision (benefit)	113	168
Net income/(loss)	422	613
Capital expenditures, net	77	10
Operating Segments | CPG
Segment Reporting Information [Line Items]
Revenues from unaffiliated customers	2,000	1,837
Costs of goods sold, inclusive of depreciation	(1,715)	(1,857)
Gross margin	$ 285	$ (20)
Gross margin %	14.30%	(1.10%)
Operating expenses:
Selling, general and administrative	$ (408)	$ (388)
Total operating expenses	2,123	2,245
Operating income/(loss)	(123)	(408)
Other income/(expense):
Other income: employee retention credit (ERC)		317
Interest expense		(1)
Total other (expense)/income, net		316
Income (loss) before income tax provision	(123)	(92)
Income tax provision (benefit)	(26)	(20)
Net income/(loss)	$ (97)	(72)
Capital expenditures, net		$ 4