CONSOLIDATED INCOME STATEMENTS - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2021
Income Statement [Abstract]
Net sales	$ 46,087	$ 42,041	$ 38,029
Cost of sales	33,338	28,909	24,454
Gross profit	12,749	13,132	13,575
Operating expenses:
Selling expenses	155	91	590
General and administrative expenses	4,028	4,903	4,076
Loss on disposal of equipment		35
Research and development costs	2,804	2,980	4,384
Total operating expenses	6,987	8,009	9,050
Operating income	5,762	5,123	4,525
Other income (expense):
Interest and dividend income	294	76	126
Unrealized gain on investments	3,899	931	1,990
Gain on sale of investments	6	28	1,327
Interest expense	(533)	(464)	(352)
Total other income	3,666	571	3,091
Income before income taxes	9,428	5,694	7,616
Income tax expense	2,354	1,122	1,446
Net income	$ 7,074	$ 4,572	$ 6,170
Basic & Diluted income per share:
Basic net income per share	$ 1.98	$ 1.26	$ 1.63
Diluted net income per share	$ 1.95	$ 1.21	$ 1.57
Weighted-average common shares outstanding:
Basic	3,571,044	3,635,894	3,796,516
Diluted	3,636,944	3,763,345	3,936,194