CONSOLIDATED CONDENSED STATEMENTS OF OPERATIONS - USD ($)	3 Months Ended		6 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
CONSOLIDATED STATEMENTS OF OPERATIONS
Net sales	$ 4,684,000	$ 3,864,000	$ 9,214,000	$ 7,955,000
Cost of goods sold	3,322,000	2,708,000	6,596,000	5,263,000
Gross profit	1,362,000	1,156,000	2,618,000	2,692,000
Operating expenses:
Engineering	273,000	240,000	539,000	447,000
Selling, general and administrative	1,358,000	1,095,000	2,644,000	2,207,000
Operating expenses	1,631,000	1,335,000	3,183,000	2,654,000
Earnings (loss) from operations	(269,000)	(179,000)	(565,000)	38,000
Other expense:
Interest expense, net	13,000	5,000	25,000	11,000
Earnings (loss) before provision (credit) for income taxes	(282,000)	(184,000)	(590,000)	27,000
Provision (benefit) for income taxes	(111,000)	(74,000)	(226,000)	12,000
Net earnings (loss)	$ (171,000)	$ (110,000)	$ (364,000)	$ 15,000
Basic earnings (loss) per share	$ (0.03)	$ (0.02)	$ (0.07)	$ 0.00