That’s the event goal - a wallet that lives on the network that can be plugged into any client. I am building it initially for my own payment service so I am no longer a ‘custodian’, but want to make it more generally available. 

 But where does the Mint live if you are not the custodian? 

 I use whatever mint is out there. The resulting ecash issued by the mint(s) live in secure events in redundant relays of your choosing, accessible only if you have the nsec. 

 And on which lightning address do you receive sats on your #safebox? 

 You have a DM