Note 10 - Income Taxes - Deferred Income Tax Assets (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Temporary differences:
Property and equipment	$ (920,000)	$ (993,000)
Intangible assets	(11,000)	(10,000)
Inventory reserve	32,000	79,000
Accrued expenses and inventory	191,000	216,000
Basis difference in investments	0	35,000
Foreign exchange	12,000	11,000
AMT/Foreign tax credits	128,000	42,000
State income taxes	(196,000)	(171,000)
Net deferred income tax liabilities	$ (764,000)	$ (791,000)