This project was put together as an entry into the 2017 "Worst Cup Ever" April Fools Contest... enjoy!
There's a classic (literally classic... as in ancient Greek classic) prank called the "greedy cup". It is also sometimes called other names like "Tantalus Cup" or "Pythagorean Cup". You can read all about it on the Pythagorean Cup Wikipedia page.
I drew up a Pythagorean-Cup-inspired siphon valve in OpenSCAD a few years ago for a hydroponic gardening project. The same thing that makes the greedy cup so devious as a prank also makes it useful for converting a continuous fluid flow into an oscillating one without any moving parts, but I digress...
When this contest came along a few days ago, I already had a working design for the siphon valve. All I had to do was draw a goblet around the valve, add a few flourishes, and... voila! I had a full working replica of a 2,000-year-old practical joke! It was probably pretty funny the first couple of times, but unfortunately, there's been a few millenia worth of diminishing returns on that joke :P
Hmmm... It was obvious that rehashing an old gag cup was not going to cut it for this contest. I needed to up my game. For inspiration, I latched on to one of the less common names assigned to this type of cup: Tantalus. Remember him? He was doomed by the gods to be forever surrounded by water but unable to take a drink. It's a fascinating story, but I won't repeat it all here. The important part of the story was that poor old Tantalus could clearly not choose the wine in front of him... or was that a different story? Nevermind. I present to you:
The Twisted Tantalus Cup!
So how does it work? Well, just like any other Pythagorean Cup, if you get greedy, you will get wet. But to remain true to the story of Tantalus, even if you don't get greedy, you will still get wet if you get thirsty. Try to take a drink, and the holes around the sides will allow your frosty libation-of-choice to dribble into your lap.
So is it hopeless? Are you, like Tantalus before you, forever doomed to the perpetual torture of an undrinkable drink??? Or does this cup contain a secret? Fire up your favorite 3D printer, try to pour yourself a glass of frosty goodness, and find out!
The cup should print on most hobby printers without any support material. I tried it with ABS on a Taz 4 at 75% scale and a 0.15mm layer height. It worked perfectly with that print. I also tried coarser prints, but the roughness of the print caused the water to not flow as well, particularly through the tiny tubes around the edge, so I'd recommend that you print this cup with as fine of a resolution as you have the patience for.
...of course if you want to ruin all the fun of discovery and skip to the solution, just keep reading (cheaters!), but don't forget what happened to Tantalus when he revealed the secrets of the gods!
*SPOILER ALERT*
*READ ON FOR THE SOLUTION*
*ARE YOU SURE YOU WANT TO KNOW ALREADY?*
Ok fine. Here's a clue: Be greedy!
Here's another clue: the solution is not "use a straw" like one of those infinity bottles.
*STILL HAVEN'T FIGURED IT OUT? THE COMPLETE SOLUTION IS BELOW*
This cup is actually pretty simple to use if you don't over-think it, but there are several red herrings that are designed to misdirect and confuse you. The holes around the edge discourage you from getting greedy or tilting the glass, and the solution to most greedy cups is usually to avoid triggering the siphon anyway. The handle is also there to trick you into putting your hands in the wrong place. If you hold this cup by the handle, you'll never drink without getting wet. Ignore all of these very visible features, and the solution then becomes obvious:
Use your forefinger and thumb on both hands to cover the four holes on the bottom of the cup, then place it under a running tap or ask a friend to fill it up while you hold it. When the siphon valve kicks in, wait until the liquid drains into the bottom chamber, then continue filling up the cup. As long as you keep your fingers over the four holes, you can drink from the Tantalus Cup just like you would drink from any other cup... because everyone knows that you should always hold your drink with two hands and with pinkies out!
And as the picture above demonstrates, there is one last dirty trick to this cup: Even if you know all of the cup's dark secrets, you will probably still be too embarrassed to actually drink from it in public!
For the practical jokers out there, I went ahead and made a non-puzzle version of this cup also. You can download the 100% pure evil non-puzzle version of the Twisted Tantalus Cup here.
Thanks for taking the time to check out my evil cup, and thanks especially to the folks who put this contest together. Win or lose, I had a lot of fun with this design, and it made me revisit some of the Greek mythology I haven't thought much about since highschool. I hope y'all enjoyed it too :)
*Post-Contest Update:
I had a chance to print one in a transparent filament at full scale on a Form 2 printer after this contest was locked in...I was pleased with the result:
-Andrew
Comments