Note 10 - Financial Information about Geographic Areas - Consolidated Net Sales and Long-lived Asset Information by Geographic Area (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 30, 2022	Mar. 31, 2021	Mar. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Net sales by geographic region
Consolidated sales	$ 17,661,000	$ 17,661,000	$ 23,161,000	$ 23,161,000
Reportable Geographical Components [Member]
Net sales by geographic region
Consolidated sales	17,661,000
Consolidated long-lived assets					$ 5,985,000	$ 6,064,000
UNITED STATES | Reportable Geographical Components [Member]
Net sales by geographic region
Consolidated sales	17,076,000		20,898,000
Consolidated long-lived assets					4,668,000	4,623,000
International Member | Reportable Geographical Components [Member]
Net sales by geographic region
Consolidated sales	$ 585,000		$ 2,263,000
Consolidated long-lived assets					$ 1,418,000	$ 1,441,000