Random Mint

[emirhansirkeci]

When somebody use my mint button i want him to receive a random NFT from this transaction.

When i use mint button (mintAmount = 2) my NFT's metadata's will be like,
ipfs://image_link/1.json
ipfs://image_link/2.json

But i dont want this. I want to receive my NFT's randomly. Like this,
ipfs://image_link/578.json
ipfs://image_link/877.json

I hope i was clear. How can i do that and can this process increase gas fees?