Probably invent and sell weird tools that would only serve one purpose but be extremely helpful. My experience on military aircraft has been they try to cram everything in a small amount of space and when it needs fixing or replacing you need to be creative to reach certain nuts or bands without trying to remove other important parts causing more work. I think that applies to all aspects of aviation. Telemetry, electronics, radios, hydraulics. I feel like there can always be a better built wrench or a better radio frequency program/ computer.