Note 8 - Geographic Segment Data - Financial Information by Geographic Area (Details) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Sales to outside customers	$ 12,406,840	$ 15,984,726	$ 24,943,229	$ 29,963,903
Assets	35,648,308		35,648,308		$ 38,760,834
Reserve	(3,000,000)		(3,000,000)
UNITED STATES
Sales to outside customers	9,095,000	12,075,000	17,855,000	21,813,000
Assets	22,907,000		22,907,000		25,354,000
Europe [Member]
Sales to outside customers	1,083,000	1,275,000	2,358,000	2,637,000
Assets	3,105,000		3,105,000		3,052,000
MEXICO
Sales to outside customers	2,022,000	2,378,000	4,103,000	4,564,000
Assets	11,490,000		11,490,000		9,476,000
UNITED KINGDOM
Sales to outside customers	207,000	$ 2,570,000	627,000	$ 950,000
UKRAINE
Assets	$ 1,146,000		$ 1,146,000		$ 879,000