Note 11 - Financial Information about Geographic Areas - Consolidated Net Sales and Long-lived Asset Information by Geographic Area (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Revenues	$ 16,053,000	$ 14,722,000	$ 45,967,000	$ 49,756,000
Reportable Geographical Components [Member]
Long-lived assets	5,543,000		5,543,000		$ 5,742,000
UNITED STATES | Reportable Geographical Components [Member]
Revenues	15,928,000	14,569,000	45,682,000	48,385,000
Long-lived assets	4,283,000		4,283,000		4,380,000
International Member | Reportable Geographical Components [Member]
Revenues	125,000	$ 153,000	285,000	$ 1,371,000
Long-lived assets	$ 1,260,000		$ 1,260,000		$ 1,362,000