Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net income	$ 5,805,000	$ 5,531,000
Adjustments to reconcile net income to cash provided by operating activities:
Purchase of marketable securities	(136,651,000)	(131,635,000)
Proceeds from sale and maturity of marketable securities	134,866,000	146,122,000
Change in value of marketable securities	(3,693,000)	1,337,000
Deferred and other income taxes	(451,000)	(2,626,000)
Depreciation and amortization	2,591,000	1,643,000
Provision for doubtful accounts	50,000	50,000
Stock-based compensation		71,000
Changes in assets and liabilities:
Accounts receivable	(680,000)	(439,000)
Costs and estimated earnings in excess of billings	4,502,000	7,433,000
Inventories	(4,413,000)	(1,724,000)
Prepaid expenses	(1,013,000)	(690,000)
Accounts payable	1,377,000	(179,000)
Customer deposits	1,391,000	1,935,000
Accrued expenses	139,000	(55,000)
Total adjustments	(1,985,000)	21,243,000
Cash flows provided by operating activities	3,820,000	26,774,000
Cash flows used in investing activities:
Acquisition of Blaw-Knox assets	(13,777,000)
Capital expenditures	(2,659,000)	(1,595,000)
Cash flows used in investing activities	(16,436,000)	(1,595,000)
Cash flows from financing activities:
Proceeds from stock option exercises	264,000	103,000
Cash flows provided by financing activities	264,000	103,000
Net increase in cash and cash equivalents	(12,352,000)	25,282,000
Cash and cash equivalents at:
Beginning of year	35,584,000	10,302,000
End of year	23,232,000	35,584,000
Non-cash investing and financing activities:
Operating lease right-of-use assets	248,000	942,000
Operating lease liabilities	$ 248,000	$ 942,000