CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net sales	$ 6,916	$ 5,162
Cost of sales	4,189	3,302
Gross profit	2,727	1,860
Operating (income) expenses:
Selling expenses	33	87
General and administrative expenses	565	504
Gain on disposal of equipment	(7)	(12)
Research and development costs	408	407
Total operating expenses	999	986
Operating income	1,728	874
Other income (expense):
Interest and miscellaneous income	74	18
Interest expense	(20)	(2)
Total other income	54	16
Income before income taxes	1,782	890
Provision for income taxes	433	262
Net income	1,349	628
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) from marketable equity investments, net of taxes	298	(109)
Comprehensive income	$ 1,647	$ 519
Basic and diluted income per share:
Net income	$ 0.31	$ 0.15
Weighted average common shares outstanding:
Basic	4,330,636	4,150,099
Diluted	4,372,893	4,189,724
Common shares outstanding	4,249,548	4,348,292