Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021
Segment Reporting Information [Line Items]
Net sales	$ 40,633	$ 33,339	$ 119,157	$ 108,762
Intersegment revenues	0	0	0	0
Earnings (loss) before income taxes	(887)	(718)	(4,830)	(1,667)
Corporate / Eliminations
Segment Reporting Information [Line Items]
Net sales	0	0	0	0
Intersegment revenues	(1,330)	(1,013)	(2,811)	(4,175)
Earnings (loss) before income taxes	(1,501)	(1,613)	(4,382)	(5,071)
Domestic Operations | Operating Segments
Segment Reporting Information [Line Items]
Net sales	29,531	25,066	89,128	83,896
Intersegment revenues	194	463	539	1,715
Earnings (loss) before income taxes	(255)	206	(2,559)	1,794
International Operations | Operating Segments
Segment Reporting Information [Line Items]
Net sales	11,102	8,273	30,029	24,866
Intersegment revenues	1,136	550	2,272	2,460
Earnings (loss) before income taxes	$ 869	$ 689	$ 2,111	$ 1,610