I was surprised myself at the seemingly complex grinding work that can be done quite easily with the grinding machines available on the colored glass market. Of course, the head consumption is somewhat higher with so much glass removal - but it's worth it.
The grinding head described here in the instructions is no longer available, since the manufacturer has generally discontinued the production of grinding heads - BUT that is not bad - because there is an even better alternative: The grinding heads from Techniglass for this application the RAPID.