Best way to make cut a semi-complex 3d model and make it into seperate objects?

I have this model that I want to cut up into multiple parts and make each part into a seperate object.

I’ve tried interesecting and then using the b-button box select with x-ray, but it’s very tedious and hard to get everything inside each interesected box selected.

Does anyone have any suggestions or ideas on how I should approach this for the best and quickest way to do this?

Thanks in advance!