Geographic Information (Details) - Financial information about foreign and domestic operations and export sales - USD ($)	3 Months Ended		9 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	$ 1,176,889	$ 1,261,161	$ 3,967,712	$ 4,034,822
UNITED STATES
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	165,000	141,000	389,000	423,000
Asia [Member]
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	404,000	653,000	1,863,000	1,973,000
Europe [Member]
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	509,000	416,000	1,226,000	1,330,000
South America [Member]
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	95,000	2,000	166,000	129,000
Middle East [Member]
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales	4,000	49,000	313,000	180,000
Other Foreign [Member]
Geographic Information (Details) - Financial information about foreign and domestic operations and export sales [Line Items]
Net Sales			$ 11,000