Condensed Balance Sheets (Parenthetical) - USD ($)	Jan. 31, 2025	Apr. 30, 2024
Trade, allowance for credit loss, current	$ 16,494	$ 34,256
Convertible preferred stock, shares authorized	1,000,000	1,000,000
Class A common stock, par value	$ 0.10	$ 0.10
Class A common stock, shares authorized	10,000,000	10,000,000
Class A common stock, shares issued	8,502,881	8,502,881
Class A common stock, shares outstanding	8,502,881	8,502,881
Treasury stock, shares	3,608,151	3,606,151
Noncumulative Preferred Stock [Member]
Convertible preferred stock, shares authorized	25,000	25,000
Convertible preferred stock, stated value	$ 20	$ 20
Convertible preferred stock, shares issued	4,100	4,100
Convertible preferred stock, shares outstanding	4,100	4,100