SonicPy and/or Processing come to my mind. Both are free.There's also Puredata. And Javascript. Also free. But, audio hardware such as a sampler (or a phone ap

SonicPy and/or Processing come to my mind. Both are free.There's also Puredata. And Javascript. Also free. But, audio hardware such as a sampler (or a phone app) might be worth considering if you don't have experience making audio mashups because when we start we don't have lived experience with creative workflows. Or to put it another way, if you've spent adult years at the computer without making audio mashups there's evidence against the computer being the right audio mashup tool for you. Good luck.