Consolidated Statements of Operations (Unaudited) - USD ($)	3 Months Ended		6 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Oct. 31, 2015	Oct. 31, 2014
Income Statement [Abstract]
Revenues	$ 6,050,772	$ 6,879,716	$ 13,388,454	$ 14,604,753
Costs and expenses:
Cost of sales	4,848,192	5,871,582	10,782,669	12,347,814
Engineering	46,280	151,734	100,239	317,289
Selling, general and administrative	1,279,723	1,667,084	2,683,989	3,311,292
Total costs and expenses	6,174,195	7,690,400	13,566,897	15,976,395
Loss from operations	(123,423)	(810,684)	(178,443)	(1,371,642)
Other income (expense):
Interest expense, net	(53,726)	$ (683,345)	(116,370)	$ (877,032)
Gain on sale of state NOL	190,462		190,462
Currency gain (loss)	6,881	$ (12,932)	7,289	$ (15,204)
Total other expense, net	143,617	(696,277)	81,381	(892,236)
Income (loss) before income taxes	$ 20,194	$ (1,506,961)	$ (97,062)	(2,263,878)
Income tax expense (benefit)				2,850
Net income (loss)	$ 20,194	$ (1,506,961)	$ (97,062)	$ (2,266,728)
Dividend – Series A preferred stock	58,949		121,609
Net loss allocated to common shareholders	$ (38,755)	$ (1,506,961)	$ (218,671)	$ (2,266,728)
Net loss per share of common stock
Basic and diluted	$ (.01)	$ (.63)	$ (.07)	$ (.94)
Weighted average common shares outstanding
Basic and diluted	3,536,037	2,410,512	3,108,422	2,410,512