Sign a transaction with Metamask

[odyslam]

I am building a simple interface for people to bundle transactions for flashbots.

I was wondering if it's possible to sign a transaction object with Metamask, as I don't want users to have to enter their private key to my website. I prefer if they trust metamask.

I understand that this is not currently possible, so I thought that perhaps it would be possible to do it manually, via signMessage.

Assuming that I have the Transaction object populated via ethers. How should I serialise it to created a signedTransaction object?

[zemse]

Atm metamask submits the message to the network on signing a transaction. If there's not really a way to prevent that, a workaround could be to get the user to switch the network to custom RPC. Then let the user to sign the transaction. Metamask would be submitting the signed transaction to the custom RPC for which you can have a proxy for eth_submitTransaction in between which doesn't submit it to the network.

(moving to discussions)