Geoff Teehan wants money to behave like a file. The design co-founder at Lightspark posted a demo this week of dotMoney, a prototype wallet for Mac, iPhone, and web. Drag money into Finder. Attach it to a message. Hand it over on a USB stick.
The trick is inside the file. A money file embeds a funded Spark wallet and carries the key to its own funds. The recipient opens the file, or a link wrapping an encrypted key, and a claim API moves the value into their own Spark wallet. Because the key travels with the file, any channel works: email, Messages, AirDrop, a USB drive, a link in a browser.
That also makes it a bearer instrument. Anyone holding an unclaimed file can spend it, just like cash. The team says so plainly: “A money file carries the key to its own funded wallet.” The prototype runs on test funds, the server holds unclaimed keys during transit, and issuance is rate limited while they work out safeguards.
Teehan is a heavyweight designer. He co-founded Teehan+Lax, the studio behind Medium’s design, then ran design at Meta as VP. His write-up says the goal was to push Lightspark’s docs and infrastructure beyond the traditional wallet, to “make digital money feel more like physical money.” 
The demo runs on Spark, Lightspark’s Bitcoin-based network layer, with test USDB. The apps are public. money.psst.gg offers Mac and iPhone TestFlight downloads, and each new wallet starts with $100 in test money. The full technical write-up is on Lightspark’s design site.
It is a design experiment, not a product launch. But it sketches a future where sending bitcoin feels like sending a photo. No addresses, no invoices, no wallet onboarding. Just a file.
