Income Taxes - Summary of Deferred Tax Assets (Liabilities) Related to Temporary Differences (Details) - USD ($)	Apr. 30, 2021	Apr. 30, 2020
Non-current tax assets (liabilities):
Less valuation allowance	$ (241,000)	$ 0
Non Current
Non-current tax assets (liabilities):
Inventories	1,241,000	924,000
Accrued expenses, including compensation	2,827,000	1,415,000
Product liability	6,000
Workers' compensation	8,000	27,000
Warranty reserve	165,000	78,000
Stock-based compensation	592,000	376,000
State bonus depreciation	51,000	43,000
Property taxes	9,000
Property, plant, and equipment	(1,696,000)	(1,705,000)
Intangible assets	3,500,000	2,219,000
Right-of Use assets	(5,879,000)	(627,000)
Right-of Use lease liabilities	6,152,000	950,000
Pension		19,000
Other	(52,000)	(139,000)
Less valuation allowance	(241,000)
Net deferred tax asset/(liability) — total	$ 6,683,000	$ 3,580,000