Note 7 - Segment Information - Net Sales for Geographic Areas (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net sales	$ 18,388,381	$ 18,628,362	$ 57,818,996	$ 58,823,494
UNITED STATES
Net sales	15,551,725	15,955,084	49,380,463	50,293,346
CANADA
Net sales	1,653,051	1,597,652	5,072,785	5,085,955
All Other Countries [Member]
Net sales	$ 1,183,605	$ 1,075,626	$ 3,365,748	$ 3,444,193