smart contract for random NFT chests

I need to develop a smart contract that allows me to create, in a marketplace that is already under development, chests in which the administrator can include several NFTs.

These NFTs have different variations: rarity, element, class, parts.

only the rarity has different percentages of probabilities of generating one or the other, the rest of the elements are totally random.

ref.
https://marketplace.plantvsundead.com/#/offering/bundle
https://marketplace.thetanarena.com/dashboard