Note 15 - Segment Reporting and Sales by Major Customer (Details Textual)	12 Months Ended
	Apr. 30, 2022
Number of Operating Segments	2
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | The Five Aerospace Customers [Member]
Concentration Risk, Percentage	34.10%
Number of Major Customers	5
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Top Customer [Member]
Concentration Risk, Percentage	14.30%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Next Top Four Customers [Member] | Minimum [Member]
Concentration Risk, Percentage	2.70%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Next Top Four Customers [Member] | Maximum [Member]
Concentration Risk, Percentage	10.70%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Customer One [Member]
Concentration Risk, Percentage	44.80%
Number of Major Customers	1