Condensed Income (Loss) Statements (Unaudited) - USD ($)	3 Months Ended		6 Months Ended
	Oct. 31, 2024	Oct. 31, 2023	Oct. 31, 2024	Oct. 31, 2023
Income Statement [Abstract]
Net Sales	$ 5,613,000	$ 6,053,000	$ 11,394,000	$ 10,781,000
Less: Cost of Goods Sold	(2,899,000)	(2,949,000)	(5,735,000)	(5,411,000)
Gross Profit	2,714,000	3,104,000	5,659,000	5,370,000
Operating Expenses
General and Administrative	417,000	333,000	755,000	702,000
Sales	787,000	787,000	1,594,000	1,476,000
Engineering	27,000	16,000	54,000	37,000
Total Operating Expenses	1,231,000	1,136,000	2,403,000	2,215,000
Income From Operations	1,483,000	1,968,000	3,256,000	3,155,000
Other (Expense)
Other	96,000	2,000	96,000	9,000
Dividend and Interest Income	299,000	217,000	616,000	458,000
Unrealized (Loss) on Equity Securities	66,000	(2,368,000)	1,413,000	(734,000)
Gain (Loss) on Investments	336,000	46,000	549,000	(71,000)
Gain (Loss) on Solar Tax Credit	373,000		373,000
Gain on Sale of Assets			(2,000)	8,000
Total Other Income (Loss)	1,170,000	(2,103,000)	3,045,000	(330,000)
Income (Loss) Before Provisions for Income Taxes	2,653,000	(135,000)	6,301,000	2,825,000
Provisions for Income Taxes:
Current Expense	465,000	543,000	1,169,000	853,000
Deferred Tax (Benefit) Expense	(27,000)	(623,000)	212,000	(347,000)
Total Income Tax Expense (Benefit)	438,000	(80,000)	1,381,000	506,000
Net Income (Loss)	$ 2,215,000	$ (55,000)	$ 4,920,000	$ 2,319,000
Income Per Share of Common Stock
Basic	$ 0.45	$ (0.01)	$ 1.00	$ 0.47
Diluted	$ 0.45	$ (0.01)	$ 1.00	$ 0.47
Weighted Average Number of Common Shares Outstanding
Basic	4,896,730	4,927,571	4,896,730	4,928,273
Diluted	4,917,230	4,927,571	4,917,230	4,948,773