CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	3 Months Ended		6 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
CONSOLIDATED STATEMENTS OF OPERATIONS
Net sales	$ 3,864,000	$ 4,155,000	$ 7,955,000	$ 8,209,000
Cost of goods sold	2,708,000	2,672,000	5,263,000	5,436,000
Gross profit	1,156,000	1,483,000	2,692,000	2,773,000
Operating expenses:
Engineering	240,000	188,000	447,000	377,000
Selling, general and administrative	1,095,000	908,000	2,207,000	1,903,000
Operating expenses	1,335,000	1,096,000	2,654,000	2,280,000
Earnings (loss) from operations	(179,000)	387,000	38,000	493,000
Other expense:
Interest expense, net	5,000	7,000	11,000	13,000
Earnings (loss) before provision for income taxes	(184,000)	380,000	27,000	480,000
Provision (credit) for income taxes	(74,000)	146,000	12,000	185,000
Net earnings (loss)	$ (110,000)	$ 234,000	$ 15,000	$ 295,000
Basic earnings per share	$ (0.02)	$ 0.04	$ 0.00	$ 0.05