Note 7 - Revenue Recognition - Net Sales by Geographic Region (Details) - USD ($)		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Net sales		$ 10,282,665	$ 9,489,504
UNITED STATES
Net sales		7,842,435	7,111,773
Australia, New Zealand [Member]
Net sales		170,122	177,048
CANADA
Net sales		158,661	199,399
MEXICO
Net sales		128,621	136,026
Europe [Member]
Net sales	[1]	962,092	938,668
Asia [Member]
Net sales	[2]	$ 1,020,734	$ 926,590

[1] Europe consists of United Kingdom, Ireland, France, Germany, Austria, and the Netherlands.

[2] Asia consists of Philippines and Malaysia.