Note 9 - Income Taxes - Income Tax Reconciliation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Expected federal tax	$ 421,000	$ 457,000
Expected federal tax, percent	21.00%	21.00%
Permanent differences	$ 2,000	$ 2,000
Permanent differences, percent	0.10%	0.10%
State income tax, net of federal tax benefit	$ 37,000	$ 54,000
State income tax, net of federal tax benefit, percent	1.90%	2.50%
Foreign tax credit	$ (4,000)	$ 8,000
Foreign tax credit, percent	(0.20%)	0.40%
Research and Development tax credit	$ (52,000)	$ (1,000)
Research and Development tax credit, percent	(2.60%)	0.00%
Other	$ (7,000)	$ 32,000
Other, percent	(0.10%)	1.40%
Total income tax expense	$ 397,000	$ 552,000
Total, percent	20.10%	25.40%