CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	3 Months Ended		9 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
CONSOLIDATED STATEMENTS OF OPERATIONS
Net sales	$ 6,094,000	$ 4,750,000	$ 19,232,000	$ 14,097,000
Cost of goods sold	4,460,000	3,680,000	12,526,000	9,874,000
Gross profit	1,634,000	1,070,000	6,706,000	4,223,000
Operating expenses:
Engineering	334,000	351,000	1,116,000	966,000
Selling, general and administrative	1,834,000	1,089,000	5,138,000	3,590,000
Operating expenses	2,168,000	1,440,000	6,254,000	4,556,000
Income from operations	(534,000)	(370,000)	452,000	(333,000)
Other expense:
Interest expense, net	27,000	36,000	77,000	84,000
Income (loss) before income tax expense	(561,000)	(406,000)	375,000	(417,000)
Income tax expense	(125,000)		61,000
Net income (loss)	$ (436,000)	$ (406,000)	$ 314,000	$ (417,000)
Basic earnings (loss) per share	$ (0.08)	$ (0.08)	$ 0.05	$ (0.08)