SELECTED QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
SELECTED QUARTERLY FINANCIAL INFORMATION (UNAUDITED) [Abstract]
Net sales	$ 54,143,638	$ 56,007,937	$ 58,044,743	$ 36,043,295	$ 34,144,942	$ 33,478,347	$ 36,883,312	$ 33,101,657	$ 204,239,613	$ 137,608,258	$ 144,567,951
Gross margin	13,842,715	11,949,531	15,513,994	8,744,579	10,862,980	9,372,742	9,202,180	6,908,308	50,050,819	36,346,210	34,249,631
Engineering expenses	1,460,670	1,848,861	1,682,887	630,411	577,056	663,704	733,009	594,538	5,622,829	2,568,307	2,459,062
Selling and administrative expenses	8,402,069	6,527,029	11,344,223	5,877,968	6,480,898	5,444,924	5,363,303	5,352,906	32,151,289	22,642,031	23,762,841
Net (loss)/income	$ (168,769)	$ 2,230,481	$ 1,466,402	$ 1,517,141	$ 2,649,349	$ 2,400,064	$ 2,087,837	$ 648,073	$ 5,045,255	$ 7,785,323	$ 5,727,043
Net (loss)/income per share [Abstract]
Basic (in dollars per share)	$ (0.03)	$ 0.36	$ 0.23	$ 0.24	$ 0.42	$ 0.38	$ 0.33	$ 0.10	$ 0.81	$ 1.25	$ 0.92
Diluted (in dollars per share)	$ (0.03)	$ 0.35	$ 0.23	$ 0.24	$ 0.42	$ 0.38	$ 0.33	$ 0.10	$ 0.80	$ 1.25	$ 0.92
Weighted average shares outstanding [Abstract]
Basic (in shares)	6,261,737	6,259,872	6,258,467	6,256,496	6,254,605	6,252,681	6,250,610	6,248,222	6,259,139	6,251,535	6,245,057
Diluted (in shares)	6,297,371	6,296,551	6,285,339	6,256,496	6,254,605	6,252,681	6,250,610	6,248,222	6,294,773	6,251,535	6,245,057