Note 13 - Quarterly Financial Data (Unaudited) - Quarterly Financial Data (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net sales	$ 24,744,403	$ 18,887,099	$ 19,177,767	$ 20,288,918	$ 24,502,272	$ 18,388,381	$ 19,280,770	$ 20,149,845	$ 83,098,187	$ 82,321,268	$ 82,923,992
Gross Profit	12,771,954	11,846,833	13,118,442	12,842,962	15,296,919	11,635,331	12,895,534	12,286,045	50,580,191	52,113,829	51,713,242
Net income	$ (628,349)	$ (121,534)	$ 1,440,092	$ 1,273,619	$ 1,671,340	$ 521,414	$ 1,027,732	$ 1,231,265	$ 1,963,828	$ 4,451,751	$ 6,402,259
NET INCOME PER COMMON SHARE:
Earnings per share – basic (in dollars per share)	$ (0.07)	$ (0.01)	$ 0.15	$ 0.14	$ 0.18	$ 0.06	$ 0.11	$ 0.13	$ 0.21	$ 0.48	$ 0.69
Earnings per share - diluted (in dollars per share)	$ (0.07)	$ (0.01)	$ 0.15	$ 0.14	$ 0.18	$ 0.06	$ 0.11	$ 0.13	$ 0.21	$ 0.48	$ 0.69
Weighted average number of common shares outstanding:
Weighted average common shares outstanding (in shares)	9,143,746	9,154,209	9,180,076	9,264,446	9,270,862	9,270,862	9,225,960	9,308,726	9,185,203	9,242,092	9,301,867
Diluted (in shares)	9,143,746	9,155,031	9,180,727	9,264,811	9,272,330	9,273,950	9,229,129	9,330,919	9,185,662	9,256,810	9,321,558
Net sales	$ 24,744,403	$ 18,887,099	$ 19,177,767	$ 20,288,918	$ 24,502,272	$ 18,388,381	$ 19,280,770	$ 20,149,845	$ 83,098,187	$ 82,321,268	$ 82,923,992
Gross Profit	12,771,954	11,846,833	13,118,442	12,842,962	15,296,919	11,635,331	12,895,534	12,286,045	50,580,191	52,113,829	51,713,242
Net income	$ (628,349)	$ (121,534)	$ 1,440,092	$ 1,273,619	$ 1,671,340	$ 521,414	$ 1,027,732	$ 1,231,265	$ 1,963,828	$ 4,451,751	$ 6,402,259