CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	3 Months Ended		9 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015
CONSOLIDATED STATEMENTS OF OPERATIONS
Net sales	$ 3,622,000	$ 3,675,000	$ 11,831,000	$ 9,471,000
Cost of goods sold	2,443,000	2,667,000	7,879,000	6,533,000
Gross profit	1,179,000	1,008,000	3,952,000	2,938,000
Operating expenses:
Engineering	195,000	203,000	572,000	557,000
Selling, general and administrative	811,000	745,000	2,714,000	2,366,000
Operating expenses	1,006,000	948,000	3,286,000	2,923,000
Earnings from operations	173,000	60,000	666,000	15,000
Other expense:
Interest expense, net	6,000	7,000	19,000	21,000
Earnings (loss) before provision for income taxes	167,000	53,000	647,000	(6,000)
Provision for income taxes	66,000	25,000	251,000	2,000
Net earnings (loss)	$ 101,000	$ 28,000	$ 396,000	$ (8,000)
Basic earnings per share	$ 0.02	$ 0.00	$ 0.07	$ 0.00