For example this question: How to render a 3D model like a blue sci-fi hologram? received a wonderful answer. But should it be migrated over? The person who answered it is a high level user on the Blender Exchange.
Two network-wide rules of thumb to keep in mind here:
- Put the question on the site that will get it a better answer. For example, if it's a question about using Blender to achieve some design goal, it can move to Blender SE. If it's a question about the design goal you happen to be using Blender for, leave it on GD SE.
- Don't migrate crap. If it's a bad question, downvote and flag (or vote) for closure. Migrating is not a way to clean up the site; it's a way to make sure each question gets the best answer it can.
Basically, don't migrate new blender questions by default. Evaluate them on a case-by-case basis. Is this a good question, but it's outside the realm of most GDSE users' Blender expertise? Migrate it. Is it a good question, and it has a good chance of getting a good answer here? Keep it.
Normally, the rule for questions that have overlapping scope like this situation is "if it's on topic, don't migrate it". For instance, a question about Aruinos asked on Electrical Engineering would not get migrated to the Arduino site.
However, I don't feel the situation to be the same here. ~10% of all questions on EE.SE are tagged with arduino. ~0.1% of our questions are tagged with blender. 3D questions on our site always feel like orphan children to me. We've agreed to take them, but they can often contrast starkly with the rest of the questions on our site.
I'm fine with migrating blender questions away from our site and giving them a better home. I discussed this with iKlsR (one of Blender's mods) who is okay with us doing so for quality questions.
If this is the consensus, then the proper way to handle them is to flag as "other (needs ♦ moderator attention)" and just make a note that you think it should be migrated to Blender.SE. I'll pop into the chat room and confirm with any active Blender members that it's a decent question worthy of migrating.
This would be for new questions only. Don't flag the existing 10 or so questions that we have tagged blender, we won't (and sometimes can't) migrate ancient questions.