Consolidated Statements of Operations (USD $)	3 Months Ended		6 Months Ended
	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2011	Oct. 31, 2010
Net sales	$ 2,711,000	$ 2,998,000	$ 5,259,000	$ 5,492,000
Cost of goods sold	1,840,000	1,970,000	3,748,000	3,567,000
Gross profit	871,000	1,028,000	1,511,000	1,925,000
Operating expenses:
Engineering	180,000	87,000	346,000	156,000
Selling, general and administrative	551,000	521,000	1,272,000	1,127,000
Operating expenses	731,000	608,000	1,618,000	1,283,000
Earnings (loss) from operations	140,000	420,000	(107,000)	642,000
Other expense (income):
Interest expense	12,000	10,000	24,000	17,000
Earnings (loss) before provision for income taxes	128,000	410,000	(131,000)	625,000
Provision for income taxes	0	0	0	0
Net earnings (loss)	$ 128,000	$ 410,000	$ (131,000)	$ 625,000
Basic earnings (loss) per share	$ 0.02	$ 0.07	$ (0.03)	$ 0.11