Note 4 - Disaggregation of Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2024	Jan. 31, 2023	Jan. 31, 2024	Jan. 31, 2023
Revenues from customers	$ 18,960	$ 20,464	$ 55,746	$ 55,093
Percentage of Completion Contracts [Member]
Revenues from customers	4,756	6,875	15,369	15,750
Transferred at Point in Time [Member]
Revenues from customers	14,204	13,589	40,377	39,343
Casino [Member]
Revenues from customers	7,319	7,210	21,816	22,745
Sportsbook [Member]
Revenues from customers	1,457	1,160	3,471	1,985
Casino Non-gaming [Member]
Revenues from customers	1,153	1,102	3,400	3,284
Professional Services [Member]
Revenues from customers	12	102	64	266
Aircraft Modification [Member]
Revenues from customers	5,402	7,188	16,967	16,902
Aircraft Avionics [Member]
Revenues from customers	810	679	2,332	1,917
Special Mission Electronics [Member]
Revenues from customers	2,807	3,023	7,696	7,994
Professional Services [Member]
Revenues from customers	9,941	9,574	28,751	28,280
Professional Services [Member] | Percentage of Completion Contracts [Member]
Revenues from customers	0	0	0	0
Professional Services [Member] | Transferred at Point in Time [Member]
Revenues from customers	9,941	9,574	28,751	28,280
Professional Services [Member] | Casino [Member]
Revenues from customers	7,319	7,210	21,816	22,745
Professional Services [Member] | Sportsbook [Member]
Revenues from customers	1,457	1,160	3,471	1,985
Professional Services [Member] | Casino Non-gaming [Member]
Revenues from customers	1,153	1,102	3,400	3,284
Professional Services [Member] | Professional Services [Member]
Revenues from customers	12	102	64	266
Professional Services [Member] | Aircraft Modification [Member]
Revenues from customers	0	0	0	0
Professional Services [Member] | Aircraft Avionics [Member]
Revenues from customers	0	0	0	0
Professional Services [Member] | Special Mission Electronics [Member]
Revenues from customers	0	0	0	0
Aerospace Products [Member]
Revenues from customers	9,019	10,890	26,995	26,813
Aerospace Products [Member] | Percentage of Completion Contracts [Member]
Revenues from customers	4,756	6,875	15,369	15,750
Aerospace Products [Member] | Transferred at Point in Time [Member]
Revenues from customers	4,263	4,015	11,626	11,063
Aerospace Products [Member] | Casino [Member]
Revenues from customers	0	0	0	0
Aerospace Products [Member] | Sportsbook [Member]
Revenues from customers	0	0	0	0
Aerospace Products [Member] | Casino Non-gaming [Member]
Revenues from customers	0	0	0	0
Aerospace Products [Member] | Professional Services [Member]
Revenues from customers	0	0	0	0
Aerospace Products [Member] | Aircraft Modification [Member]
Revenues from customers	5,402	7,188	16,967	16,902
Aerospace Products [Member] | Aircraft Avionics [Member]
Revenues from customers	810	679	2,332	1,917
Aerospace Products [Member] | Special Mission Electronics [Member]
Revenues from customers	2,807	3,023	7,696	7,994
North America [Member]
Revenues from customers	15,104	17,832	48,098	50,833
North America [Member] | Professional Services [Member]
Revenues from customers	9,941	9,574	28,751	28,280
North America [Member] | Aerospace Products [Member]
Revenues from customers	5,163	8,258	19,347	22,553
Europe [Member]
Revenues from customers	2,255	90	3,873	396
Europe [Member] | Professional Services [Member]
Revenues from customers	0	0	0	0
Europe [Member] | Aerospace Products [Member]
Revenues from customers	2,255	90	3,873	396
Asia [Member]
Revenues from customers	876	92	1,235	503
Asia [Member] | Professional Services [Member]
Revenues from customers	0		0	0
Asia [Member] | Aerospace Products [Member]
Revenues from customers	876	92	1,235	503
Australia and Other [Member]
Revenues from customers	725	2,450	2,540	3,361
Australia and Other [Member] | Professional Services [Member]
Revenues from customers	0	0	0	0
Australia and Other [Member] | Aerospace Products [Member]
Revenues from customers	$ 725	$ 2,450	$ 2,540	$ 3,361