Major Customers (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) customer	Jun. 30, 2020 USD ($)
Revenue, Major Customer [Line Items]
Number of major customers | customer			5
Net sales	$ 80,461	$ 37,806	$ 153,290	$ 101,830
Product
Revenue, Major Customer [Line Items]
Net sales	79,117	35,847	148,251	97,777
Tooling
Revenue, Major Customer [Line Items]
Net sales	1,344	1,959	5,039	4,053
UFP
Revenue, Major Customer [Line Items]
Net sales	15,115	9,484	25,772	18,471
UFP | Product
Revenue, Major Customer [Line Items]
Net sales	15,115	9,484	25,772	18,471
UFP | Tooling
Revenue, Major Customer [Line Items]
Net sales	0	0	0	0
Navistar
Revenue, Major Customer [Line Items]
Net sales	10,969	7,588	21,212	18,352
Navistar | Product
Revenue, Major Customer [Line Items]
Net sales	10,969	6,500	20,906	17,166
Navistar | Tooling
Revenue, Major Customer [Line Items]
Net sales	0	1,088	306	1,186
Volvo
Revenue, Major Customer [Line Items]
Net sales	7,456	2,789	17,601	11,887
Volvo | Product
Revenue, Major Customer [Line Items]
Net sales	7,429	2,167	17,554	9,740
Volvo | Tooling
Revenue, Major Customer [Line Items]
Net sales	27	622	47	2,147
PACCAR
Revenue, Major Customer [Line Items]
Net sales	11,333	3,167	21,016	11,323
PACCAR | Product
Revenue, Major Customer [Line Items]
Net sales	10,830	3,167	20,184	11,116
PACCAR | Tooling
Revenue, Major Customer [Line Items]
Net sales	503	0	832	207
BRP
Revenue, Major Customer [Line Items]
Net sales	10,544	2,319	19,227	9,786
BRP | Product
Revenue, Major Customer [Line Items]
Net sales	10,420	2,206	18,989	9,453
BRP | Tooling
Revenue, Major Customer [Line Items]
Net sales	124	113	238	333
Other Customers
Revenue, Major Customer [Line Items]
Net sales	25,044	12,459	48,462	32,011
Other Customers | Product
Revenue, Major Customer [Line Items]
Net sales	24,354	12,323	44,846	31,831
Other Customers | Tooling
Revenue, Major Customer [Line Items]
Net sales	$ 690	$ 136	$ 3,616	$ 180