Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
	Aug. 31, 2014	Aug. 31, 2013
Operating activities:
Net income	$ 392,306	$ 201,263
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation	185,628	178,110
Stock options issued for services	37,112	43,301
Changes in other assets and liabilities:
Accounts receivable	(366,555)	(392,649)
Inventory	331,491	339,315
Costs and estimated earnings in excess of billings	(1,148,099)	(664,096)
Other current assets	(9,274)	(80,341)
Accounts payable	620,836	(144,866)
Accrued commissions	23,291	79,386
Billings in excess of costs and estimated earnings	537,975	(4,041)
Other current liabilities	210,971	(970,688)
Net operating activities	815,682	(1,415,306)
Investing activities:
Acquisition of property and equipment	(110,388)	(667,389)
Other investing activities	(1,335)	(1,350)
Net investing activities	(111,723)	(668,739)
Financing activities:
Proceeds from issuance of common stock, net	4,221	160,558
Net financing activities	4,221	160,558
Net change in cash and cash equivalents	708,180	(1,923,487)
Cash and cash equivalents - beginning	3,501,822	2,793,642
Cash and cash equivalents - ending	$ 3,501,822	$ 74,387