Statements of Comprehensive Income (Unaudited) - USD ($)	3 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Net sales	$ 5,923,819	$ 8,337,399
Cost of sales	4,787,471	7,344,465
Gross profit	1,136,348	992,934
Selling, general and administrative expenses	1,084,212	1,009,544
Operating income (loss)	52,136	(16,610)
Other income:
Interest income	32,161	52,399
Other	15,328	23,671
Total other income	47,489	76,070
Income before provision (benefit) for income taxes	99,625	59,460
Provision (benefit) for income taxes	17,849	(2,211)
Net income	81,776	61,671
Other comprehensive income, net of tax:
Unrealized gain on investment securities	197	1,347
Total comprehensive income	$ 81,973	$ 63,018
Net income per share:
Basic	$ 0.03	$ 0.03
Diluted	$ 0.03	$ 0.03
Weighted average number of shares outstanding:
Basic	2,387,408	2,359,493
Diluted	2,396,256	2,382,072
Dividends per share:	$ 0.25	$ 1.25