The DuraMold was one of the coolest styles of arcade cabinets ever made (it ranks up there with the Tron Environmentals and the experimental bug headed Space Invaders machines).
DuraMold games came in a round cabinet made completely out of thick (almost indestructible) plastic. This was an experiment in making an indestructible arcade cabinet that would last forever. They succeeded as far as that goes, it is almost impossible to damage a DuraMold cabinet. But they had an unforseen problem that proved to be fatal.
The problem with the DuraMold is that they shrank ever so slightly (over time). This shrinking (in some cases), could cause the monitor to violently eject from the machine as if shot from a gun. Luckily (for Williams sake), no one was ever killed by one of these things. But it only takes a couple of flying monitors to give a cabinet a bad name, and soon Williams was unable to sell any of them (even after they fixed the problem).
There were only three games released in this cabinet (Williams had originally planned to replace their entire line of uprights with these DuraMolds), they were, Bubbles, Sinistar, and Blaster. The Blaster and Sinistar cabinets were black, and the Bubbles ones were blue (there are also rumors of a red Sinistar, but no one seems to be able to provide a photo of one).
Today the DuraMold cabinet is highly collectable, because of its good looks, durability, and the quality of the games that came in them. The flying monitor syndrome is no longer a problem (if it was going to happen to a particular game, then it would have happened back in 1983). DuraMold cabinets are rare, but it seems that the majority of them have survived to the modern day. This is because they are hard to damage, and are nearly impossible to get rid of. Even if you threw one away it would just sit there in the dump, waiting to be discovered (it isn't like these things biodegrade like wood does).
Expect to pay a lot for one of these cabinets (even for an empty one). Sinistar ones especially can go for thousands of dollars (there were only 500 of those made). The Bubbles and Blaster models are a little more common.
Excerpts from the "DuraMold" letter that came with Bubbles
(I typed this in from a scan of an original)
You have just obtained a Bubbles Video Game with an experimental molded plastic cabinet. We at Williams electronics need your help to monitor player reaction and identify any problems that may occur with this game over the next few weeks.
While the experimental production run was limited to a small percentage of Bubbles games, we anticipate that this innovative cabinet design will result in increased player appeal and prove to be more durable in a location environment.
Feedback from you, pro or con, will hep us decide if we should use this cabinet on a future game. Please do not hesistate to call us toll free at 800-621-1253 (In Illinois 800-572-1324) If you have any suggestions, praise, or other comments.