> You can also use e-cash non custodially if you run your own mint Running your own mint, using it to mint ecash for yourself does not improve privacy. You might as well run LN node instead and use LN with self custody. Recipient needs to be online for redeeming e-cash if its issues by untrusted mint. > though I want to have e-cash if I must use a custodian Why do you need a custodian in the first place? Whole point of creating bitcoin was to create e-cash with no trusted third parties. You can read old discussions on mailing lists, whitepaper and initial website. > Users of lightning can benefit from the liquidity without using custodians themselves AFAIK e-cash is used for small amount. Lightning already gets enough liquidity from boltz swaps, centralized exchanges etc. Ark and Mercury could provide more liquidity in the future without involving trusted third parties.