Note 8 - Geographic Segment Data - Financial Information by Geographic Area (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Sales to outside customers	$ 5,745,353	$ 9,202,406	$ 12,812,854	$ 17,882,423
Assets	24,259,486		24,259,486		$ 31,321,083
Assets Held for Sale International Subsidiaries	788,000		788,000		756,000
UNITED STATES
Sales to outside customers	4,543,000	7,180,000	9,969,000	13,779,000
Assets	15,163,000		15,163,000		19,668,000
MEXICO
Sales to outside customers	1,202,000	$ 2,022,000	2,844,000	$ 4,103,000
Assets	$ 8,308,000		$ 8,308,000		$ 10,897,000