Note 17 - Segment and Related Information - Information by Industry Segment (Details) - USD ($)		3 Months Ended								12 Months Ended
		Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Sales		$ 27,320,481	$ 26,397,857	$ 26,449,885	$ 23,994,004	$ 19,933,941	$ 21,277,797	$ 18,576,588	$ 25,281,574	$ 104,162,227	$ 85,069,900
Gross Profit		4,371,546	5,397,709	5,780,290	6,002,921	4,371,691	4,852,417	3,499,039	6,208,143	21,912,465	18,931,290
Operating Income		676,214	1,868,781	2,119,797	2,325,460	1,657,368	2,126,417	530,520	3,138,149	6,990,252	7,452,453
Pretax Income										7,362,942	7,475,241
Net Income (Loss)		$ 64,698	$ 1,197,877	$ 1,247,305	$ 3,143,417	$ 2,108,890	$ 1,426,090	$ 228,837	$ 2,075,570	5,653,298	5,839,387
Commercial Air Handling [Member]
Sales										38,018,412	41,243,413	[1]
Gross Profit										7,749,628	10,216,587	[1]
Operating Income										3,065,156	5,313,487	[1]
Pretax Income										3,071,119	5,750,226	[1]
Net Income (Loss)										2,303,339	4,312,669	[1]
Aerospace [Member]
Sales										66,143,815	43,826,487	[1]
Gross Profit										14,162,131	8,714,703	[1]
Operating Income										4,519,290	2,008,958	[1]
Pretax Income										4,209,308	1,298,632	[1]
Net Income (Loss)										3,468,366	1,004,430	[1]
Industrial Hose [Member]
Sales	[1]										0
Gross Profit										706	0	[1]
Operating Income										(594,194)	130,008	[1]
Pretax Income										82,515	696,383	[1]
Net Income (Loss)										(118,407)	522,288	[1]
Corporate and Other [Member]
Sales										104,162,227	85,069,900	[1]
Gross Profit										21,912,465	18,931,290	[1]
Operating Income										6,990,252	7,452,453	[1]
Pretax Income										7,362,942	7,745,241	[1]
Net Income (Loss)										$ 5,653,298	$ 5,839,387	[1]

[1] Segment information for the twelve months ended December 31, 2020 has been restated to reflect the change in reportable segments.