Statements of Comprehensive Income (Loss) (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Net sales	$ 6,191,300	$ 9,218,141	$ 19,401,793	$ 24,858,649
Cost of sales	5,280,367	7,067,702	15,874,364	20,199,041
Gross profit	910,933	2,150,439	3,527,429	4,659,608
Selling, general and administrative expenses	1,057,034	1,069,070	3,390,988	3,374,301
Operating (loss) income	(146,101)	1,081,369	136,441	1,285,307
Other income
Interest income	20,127	38,623	86,203	133,398
Other	3,391	6,631	23,568	41,288
Total other income	23,518	45,254	109,771	174,686
(Loss) income before (benefit) provision for income taxes	(122,583)	1,126,623	246,212	1,459,993
(Benefit) provision for income taxes	(18,818)	204,167	39,237	258,107
Net (loss) income	(103,765)	922,456	206,975	1,201,886
Other comprehensive income, net of tax:
Unrealized gain on investment securities	1,130	1,512	972	3,766
Total comprehensive (loss) income	$ (102,635)	$ 923,968	$ 207,947	$ 1,205,652
Net (loss) income per share:
Basic	$ (0.04)	$ 0.39	$ 0.09	$ 0.51
Diluted	$ (0.04)	$ 0.39	$ 0.09	$ 0.50
Weighted average number of shares outstanding:
Basic	2,394,727	2,378,332	2,391,247	2,369,527
Diluted	2,394,727	2,388,781	2,395,787	2,388,258
Dividends per share:	$ 0.25	$ 0.25	$ 0.75	$ 1.75