Note K - Business Segments and Foreign Operations - Geographic Information (Details) - USD ($)	12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Net sales	$ 340,738,000	$ 295,127,000
Long-lived assets	89,583,000	77,402,000
Reportable Geographical Components [Member] | UNITED STATES
Net sales	87,549,000	79,823,000
Long-lived assets	39,949,000	39,475,000
Reportable Geographical Components [Member] | NETHERLANDS
Net sales	52,735,000	46,162,000
Long-lived assets	11,426,000	10,270,000
Reportable Geographical Components [Member] | FINLAND
Net sales	24,618	0
Long-lived assets	15,660,000	14,362,000
Reportable Geographical Components [Member] | CHINA
Net sales	28,666,000	45,527,000
Reportable Geographical Components [Member] | BELGIUM
Long-lived assets	8,184,000	5,746,000
Reportable Geographical Components [Member] | CANADA
Long-lived assets	5,952	0
Reportable Geographical Components [Member] | AUSTRALIA
Net sales	22,358,000	17,790,000
Reportable Geographical Components [Member] | Other Countries [Member]
Net sales	114,392,000	89,011,000
Long-lived assets	8,412,000	7,549,000
Reportable Geographical Components [Member] | ITALY
Net sales	$ 10,420,000	$ 16,814,000