We built a Bitcoin Keurig coffee maker this weekend (opens in new tab)

The amount of time it takes you to create a US Dollar isn't how you would measure the cost of something. It's strictly based on the value of that item. And with .0015 Bitcoin being equivalent to just over $1 USD, it's not much markup. A k-cup can easily cost $.75/each.

0.0015 Bitcoin = 850 Dogecoin (I just looked it up) ... less than a day of mining on mid-to-high-end current or last gen AMD Cards (79XX, or R9-280X+).

GPU mining Bitcoin has been unprofitable for like over a year.

Perhaps BTC does have a liquidity problem.

Only twenty minutes or so, so the coffee might be a bit lukewarm, but it's ok as you'll be living in the future!

Seriously though, this is a really cool fun hack, but I doubt it is meant to be actually useful, or that bitcoins will be ready for vending machines any time soon.

I'm not sure if you're being serious or not, but the cost of double spending is vastly higher than the value of the coffee.

The risk of accepting on 0 confirmations is probably lower than that of accepting fake currency or the cost of processing a credit card.

Tossing some of these in the trash appears to be only slightly worse than tea bags: http://myworldinacup.com/ Just ordered some to try.

Also you can get a reusable filter basket and then grind and dose like a normal person.

Was worried about the same thing when ordering a replacement for an aging Aeropress lately. IIRC Keurig's website says they care about the environment blah blah blah and have been "working on it" for a while, but no concrete promises.

It's an always-on kettle with a semi-pressurized, single-serve coffee maker attached.

PSA: nobody should buy the standard plastic K-Cups.

Risky - is possible but you would basically be trusting the machine (or anyone else who scans the cup) not to steal all your money. You could limit the damage with a separate wallet I guess, but generally the payer should be the one initiating the transaction, actively and not passively. Maybe when M of N transactions are implemented, this type of thing would be more feasible?