Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Feb. 28, 2023	Feb. 28, 2022
Operating activities
Net income	$ 4,220,766	$ 724,388
Adjustments to reconcile net income to net cash flows from operating activities
Depreciation	1,003,924	980,525
Stock options issued for services	128,437	125,764
Changes in other assets and liabilities
Accounts and other receivables, net	(4,096,679)	(1,147,600)
Inventory	414,140	38,591
Costs and estimated earnings in excess of billings	(437,513)	178,192
Other current assets	(113,378)	109,225
Accounts payable	40,323	(617,153)
Billings in excess of costs and estimated earnings	315,233	(653,856)
Other current liabilities	(134,605)	649,968
Net operating activities	1,340,648	388,044
Investing activities
Acquisition of property and equipment	(2,382,514)	(721,969)
Purchase of short-term investments	(18,179,193)	(4,692)
Other investing activities	(3,624)	(3,679)
Net investing activities	(20,565,331)	(730,340)
Financing activities
Proceeds from issuance of common stock, net	91,492	12,335
Net change in cash and cash equivalents	(19,133,191)	(329,961)
Cash and cash equivalents - beginning	22,517,038	20,581,604
Cash and cash equivalents - ending	$ 3,383,847	$ 20,251,643