Condensed Consolidated Statements of Income - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Net sales	$ 10,340,600	$ 9,936,900	$ 30,657,000	$ 24,274,800
Operating costs and expenses:
Cost of sales	5,420,000	5,830,600	16,649,000	13,454,600
Advertising	109,800	91,700	531,100	1,426,600
Selling	1,583,400	1,717,300	4,878,600	4,184,300
General and administrative	1,062,700	1,218,800	3,166,300	3,433,000
Total operating costs and expenses	8,175,900	8,858,400	25,225,000	22,498,500
Income from operations	2,164,700	1,078,500	5,432,000	1,776,300
Other income		1,000		12,600
Interest expense	(26,400)	(60,400)	(101,500)	(77,500)
Income before income taxes	2,138,300	1,019,100	5,330,500	1,711,400
Income tax expense	(663,500)	(415,500)	(1,899,300)	(697,900)
Net income	$ 1,474,800	$ 603,600	$ 3,431,200	$ 1,013,500
Net income per common share
Basic	$ 0.12	$ 0.05	$ 0.29	$ 0.09
Diluted	$ 0.12	$ 0.05	$ 0.28	$ 0.08
Weighted average shares outstanding:
Basic	11,885,839	11,747,612	11,840,957	11,730,759
Diluted	12,360,079	12,027,956	12,217,890	11,969,167