Note 13 - Segment and Related Information - Information by Industry Segment (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Sales	$ 31,902,027	$ 26,449,885	$ 62,904,773	$ 50,443,889
Gross Profit	6,768,491	5,780,290	13,134,897	11,783,211
Operating Income	2,375,527	2,119,797	3,772,849	4,445,257
Pretax Income	1,595,670	1,594,457	3,236,761	5,263,416
Net Income	1,171,264	1,247,305	2,237,139	4,390,722
Commercial Air Handling [Member]
Sales	11,845,380	9,972,545	23,403,254	18,737,644
Gross Profit	2,453,139	2,030,038	5,082,796	4,260,858
Operating Income	1,382,553	845,092	2,944,897	1,890,721
Pretax Income	1,382,553	845,092	2,944,897	1,890,721
Net Income	988,526	633,818	2,105,602	1,418,040
Industrial and Transportation Products [Member]
Sales	20,056,647	16,477,340
Gross Profit	4,315,352	3,750,252
Operating Income	1,839,634	1,342,966
Pretax Income	1,514,121	1,121,507
Net Income	1,071,636	893,184
Aerospace [Member]
Sales			39,501,519	31,706,245
Gross Profit			8,052,101	7,522,353
Operating Income			3,121,620	3,094,411
Pretax Income			2,930,092	2,693,643
Net Income			2,017,870	2,099,368
Corporate and Other [Member]
Sales		0	62,904,773	50,443,889
Gross Profit	0	0	13,134,897	11,783,211
Operating Income	(846,660)	(68,261)	3,772,849	4,445,257
Pretax Income	(1,301,004)	(372,142)	3,236,761	5,263,416
Net Income	$ (888,898)	$ (279,697)	2,237,139	4,390,722
Industrial Hose [Member]
Sales			0	0
Gross Profit			0	0
Operating Income			(2,293,668)	(539,875)
Pretax Income			(2,638,228)	679,052
Net Income			$ (1,886,333)	$ 873,314