The Legend of the Chrome Cup
/Today, we dive into the most beloved part by LEGO GBC (Great Ball Contraption) builders: the chrome cup. This rare and elusive part typically sells for 6 euros ($6.50 USD) on BrickLink and is being hoarded by some of the greatest builders—and it isn’t because it is shiny.
Animated gif by Frederik hareide.
Where did the part originate from, and why has it only ever been produced in one color? Why is the chrome cup being hoarded by GBC builders? And are there any alternatives? Read on to learn about the legend of the chome cup.
History of The Legendary Chrome Cup
The chrome cup was released long before the first LEGO GBC ball existed in 1993. It was featured in sets 9701-1 and 9702-1 as part of the Educational & Dacta Control Lab sets. As the BrickLink name suggests, the part’s primary function is to reflect the light in a beam (the BrickLink name is “Chrome Silver Dish 2 x 2 x 2/3 Light Reflector”).
After looking through the different builds from this set, I also noticed that the chrome cup in the alternate build 9701-3 was designed to work with the light brick included in the set.
demonstration of set 9702-1 in action. video by Battery powered bricks.
The chrome cups were not limited to sets with light bricks or in Technic sets. Like with many Technic parts, other LEGO designers probably found the part exciting and started using the chrome cups in various themed sets… and even some very exclusive sets. The chrome cup was in production between 1993 and 2005, and 37 sets in total included it.
As the name of this article suggests, the chrome cup is only finished in a silver chrome coating, much like the original golden pirate coins. I could not discover any prototype in different finishes, nor any other element using the same mold but in a different color. The plastic on the inside is a muddled grey, leading me to believe it was either recycled colors that LEGO knew would be coated or some other uncolored ABS.
Why Is The Chrome Cup So Rare? (And Expensive?)
Of the 37 sets the chrome cup appeared in, I would consider only 21 of those sets were available to regular consumers. The other 16 sets are educational ones, service packs or rare exclusives. Of the 21 generally available sets, five are from the Model Team product line and two are Train sets which are more valuable as complete sets with the chrome cups included.
That lowers our pool of sets to part out to only 14. Out of the 14 remaining sets, there are only an average of two chome cups per set. I should also remind you that the chrome cup was available for sale at a time frame when LEGO was not selling as many sets as they are selling today, so the volume is not what you might expect. All of these factors increase the rarity of a part, and that doesn’t include the fact that it is shiny. Some builders hoard shiny pieces, never to be seen on the market again.
But the final blow to the availability of the chrome cup came when Akiyuki released their first GBC module. The movement was elegant and mesmerizing and changed the GBC landscape. The hunt for chrome cups was on.
As you can imagine, the average price on BrickLink is eye-watering at 3.56 Euro (used) and 5.96 Euro (new). At those prices, it can make building GBC modules quite a bit more expensive when using the chrome cup. When I started building GBC modules back in 2019, I had no chrome cups and I did not want to pay 6 Euros for one part, so I looked for alternative options to get my hands on some.
After considering many options, I found that the best way to get my hands on chrome cups was by purchasing set 6568-1 from second-hand market places. You can typically find the set for around 15~20 Euros—and it includes four chrome cups! The four cups alone have a used value of 14.24 Euros, so for just a little extra, you get 266 other parts which is a good deal!
Why Is the Chrome Cup the GBC Holy Grail?
To find out how the GBC ball fits perfectly in the chrome cup, I asked a friend of mine who is really good with 3D software to make a cutaway view of the chrome cup and a GBC ball. This way, we can see the radius of the cup and compare it to the GBC ball:
RENDER made by FREDRIK HAREIDE
As you can see, the GBC ball has a larger radius (14.08mm) than the chrome cup (13.49mm). This means that there is a small contact area between the GBC ball and the cup. The GBC ball is sitting on top of the cup but is still able to drop a few millimeters into the cup—and because it can drop into the cup a bit, it can stay in place if the cup moves. This is an extremely useful coincidence for GBC builders! Akiyuki made a second module with the chrome cup that uses all of its geomentric benefits to their full potential.
Due to the almost perfect fit, the balls stay inside the cup even though the angle constantly changes. Only when the cup is at about 80 degrees does it fall out of the cup into the next one. If you can’t get enough of watching these shiny cups moving balls, I made a list of a few of the modules that use the chrome cup one way or another:
Although the chrome cup is by far the best part for GBC modules that need to shoot, hold or move a ball, the chrome cup is also used by other MOC builders. Here are a few examples of LEGO creations made with the chrome cup.
Alternatives For the Chrome Cup
Because of the rarity of the chrome cup, there is always a search for the next best part to scoop up GBC balls. It has turned into a challenge to see what inventive ways are possible to pass balls from cup to cup. Here are some of the options the community has discovered so far:
Creativity is the community’s only limitation in replacing the chrome cup. Just take a look at the chair-to-chair module (using part 4079b) and the Helmet2Helmet module (using part 30172).
In my opinion, there are multiple alternatives to the chrome cup. The best piece I’ve found so far is the eggshell. It has a similar shape to the cup but has a bit less contact with the ball. That means if the module shakes or vibrates, the ball is more likely to fall out of the shell. But the eggshell is a LOT cheaper than the chrome cup, only costing about 0.05 Euros each.
One final alternative is the crown element introduced in the Angry Birds sets from 2016. It has a worse grip than the eggshell piece but has the added ability to essentially grab the ball because of the flexibility of the crown’s tips—a feat not possible with the chrome cup and the eggshell.
All in all, the Chrome Cup is one of the most iconic LEGO elements for GBC builders. The perfect fit of ball and cup makes so many movements possible. So if you ever find a shiny chrome cup in your collection, gift it to a GBC builder. It is as rare as a goat and they will be very happy to receive such a shiny present!
Do you have any chrome cups in your collection? Let us know in the comments below!
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