Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended		6 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012	Oct. 31, 2011
Income Statement [Abstract]
Revenues	$ 6,959,023	$ 10,406,008	$ 14,957,508	$ 20,675,814
Costs and expenses:
Cost of sales	5,771,958	7,885,229	12,076,405	15,260,699
Engineering	189,728	197,927	395,836	379,363
Selling, general and administrative	2,189,278	3,376,004	4,543,495	6,829,095
Total costs and expenses	8,150,964	11,459,160	17,015,736	22,469,157
Loss from operations	(1,191,941)	(1,053,152)	(2,058,228)	(1,793,343)
Other income (expense):
Interest expense, net	(71,368)	(95,619)	(142,750)	(198,217)
Currency gain (loss), net	15,552	(30,103)	(22,496)	(41,271)
Total other expense, net	(55,816)	(125,722)	(165,246)	(239,488)
Loss before income taxes	(1,247,757)	(1,178,874)	(2,223,474)	(2,032,831)
Income tax expense
Net loss	$ (1,247,757)	$ (1,178,874)	$ (2,223,474)	$ (2,032,831)
Net loss per share of common stock
Basic	$ (0.12)	$ (0.11)	$ (0.21)	$ (0.19)
Diluted	$ (0.12)	$ (0.11)	$ (0.21)	$ (0.19)