STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Net sales	$ 27,172	$ 22,465
Cost of sales	17,392	14,522
Gross profit	9,780	7,943
Operating (income) expenses:
Selling expenses	415	358
General and administrative expenses	2,492	2,287
Asset impairment charges		1,029
Gain on disposal of equipment	(7)	(16)
Research and development costs	1,882	1,893
Total operating expenses	4,782	5,551
Operating income	4,998	2,392
Other income (expense):
Interest and dividend income	268	225
Other income	45
Gain on sale of investments	356
Interest expense	(220)	(7)
Total other income	449	218
Income before income taxes	5,447	2,610
Income tax expense	1,299	989
Net income	4,148	1,621
Other comprehensive loss, net of tax:
Unrealized loss from marketable equity investments, net of income taxes	(396)	(186)
Comprehensive income	$ 3,752	$ 1,435
Basic & Diluted income per share:
Basic net income per share	$ 0.99	$ 0.38
Diluted net income per share	$ 0.97	$ 0.37
Weighted average common shares outstanding:
Basic	4,192,365	4,304,602
Diluted	4,298,332	4,344,765