Note 8 - Geographic Segment Data - Net Sales to Outside Customers (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Net Sales	$ 6,234,231	$ 5,980,766	$ 19,975,640	$ 18,793,620
UNITED STATES
Net Sales	5,183,446	4,616,118	17,494,388	14,584,541
MEXICO
Net Sales	$ 1,050,785	$ 1,364,648	$ 2,481,252	$ 4,209,079