Custom Hitbox Entity/Block

It would be awesome for mapakers to be able to create custom hitboxes for their models

My suggestion would be to either add an entity which can have custom hitbox for example indicated with relative size coordinates from the entity's origin and thus to make a more complex hitbox you simply use many entities

or

a block which is 'subdivided' in 4096(16x16x16)/ 512(8x8x8) /64(4x4x4) /8(2x2x2) 'miniblocks' which work as hitboxes, and through commands we can choose the resolution and the placements of these miniblocks to create a custom hitbox that can be more complex and requires a single block.

To make easier to understand, it would be similar to the Chisel mod's miniblocks, but only with hitbox (this is just an example and not a suggestion to add the Chisel mod to vanilla)