Statements of Income - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Net sales	$ 13,599,084	$ 13,445,565
Costs and expenses:
Cost of sales	5,657,353	5,343,459
Operating expenses	2,148,375	2,122,746
Research and development	397,391	399,517
Total costs and expenses	8,203,119	7,865,722
Income from operations	5,395,965	5,579,843
Other income (expense):
Investment income	203,329	231,986
Net gain (loss) on marketable securities	431,076	(333,138)
Loss on trade-in of equipment		(12,837)
Total other income (expense)	634,405	(113,989)
Income before provision for income taxes	6,030,370	5,465,854
Provision for income taxes	1,268,659	1,113,523
Net income	$ 4,761,711	$ 4,352,331
Earnings per common share (basicand diluted) (in dollars per share)	$ 1.04	$ 0.95
Weighted average shares (basic and diluted) (in shares)	4,594,319	4,594,319