Inventories - Schedule of Inventories (Details) - USD ($)	Jul. 31, 2019	Apr. 30, 2019
Inventory Disclosure [Abstract]
Raw materials	$ 3,878,000	$ 3,644,000
Work in process	368,000	389,000
Finished goods	715,000	641,000
Inventory gross	4,961,000	4,674,000
Less: allowance for obsolete inventory	(98,000)	(91,000)
Inventories, net	$ 4,863,000	$ 4,583,000

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Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.

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Gross amount, as of the balance sheet date, of merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Amount before valuation and LIFO reserves of raw materials expected to be sold, or consumed within one year or operating cycle, if longer.

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Amount of valuation reserve for inventory.

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Amount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed within one year or operating cycle, if longer.

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