Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019	Dec. 28, 2019
Revenue	$ 15,729	$ 13,974	$ 52,871	$ 39,758
Gross profit	$ 1,144	$ 1,675	$ 6,857	$ 4,955
Gross profit margin	7.30%	12.00%	13.00%	12.50%
SG&A	$ 2,174	$ 2,371	$ 6,621	$ 7,125
Operating income (loss)	(1,030)	(696)	236	(2,170)
Other income, net	4	7	6	48
Interest expense, net	(62)	(5)	(103)	(12)
Tax expense	(22)	(22)	(80)	(73)
Net income (loss)	(1,110)	(716)	59	(2,207)
Total assets	32,945		32,945		$ 28,686
EPCM
Revenue	8,016	4,256	19,771	15,548
Gross profit	$ 754	$ 75	$ 1,677	$ 1,574
Gross profit margin	9.40%	1.80%	8.50%	10.10%
SG&A	$ 574	$ 651	$ 1,852	$ 1,826
Operating income (loss)	180	(576)	(175)	(252)
Total assets	9,888		9,888		6,253
Automation
Revenue	7,713	9,718	33,100	24,210
Gross profit	$ 390	$ 1,600	$ 5,180	$ 3,381
Gross profit margin	5.10%	16.50%	15.60%	14.00%
SG&A	$ 417	$ 427	$ 1,121	$ 1,246
Operating income (loss)	(27)	1,173	4,059	2,135
Total assets	10,350		10,350		13,603
Corporate
Revenue	0	0	0	0
Gross profit	$ 0	$ 0	$ 0	$ 0
Gross profit margin	0.00%	0.00%	0.00%	0.00%
SG&A	$ 1,183	$ 1,293	$ 3,648	$ 4,053
Operating income (loss)	(1,183)	$ (1,293)	(3,648)	$ (4,053)
Total assets	$ 12,707		$ 12,707		$ 8,830