The most prominent two brands that produce silicone-based custom IEMs are ACS and Sensaphonics, but their products are very stage-oriented, and are not always the ideal sound signature for personal listening, especially if you want something similar to the 1Plus2. Companies like Minerva are also stage-oriented in nature. Other than Spiral Ear, two brands that you can take note of are
CustomArt and
Noble Audio.
CustomArt, like Spiral, produces CIEMs in Poland. The founder,
Peter, is currently working on a flagship model, codenamed 'Harmony', that is slated to be released early next year. He has a prototype at the moment, and despite positive impressions from people, Peter isn't satisfied with the sound and wants to make it significantly better. Here's the CustomArt thread, where you can find more information: http://www.head-fi.org/t/663051/new-custom-iem-company-custom-art-discussion-review-and-appreciation-thread
Noble Audio, --- brainchild of the
Wizard,
Brannan Mason & Co., on the other hand, offers silicone-based variants of their 3C, 4C, 5C models in the 3S, 4S, and 5S. While none of the three are considered "flagship" models of the Noble product lineup (the flagship model is only available in acrylic), the 4S was
received very well by
ljokerl, who ranks it among the very best of the CIEMs that he's heard.