<p>As you may or may not know, this is the third iteration of a proposal site that covers 3D Printing. The first 2 made it to the beta phase, but did not graduate  from the beta successfully:</p>

<ul>
<li><a href="http://area51.stackexchange.com/proposals/41850/digital-fabrication">Digital Fabrication</a></li>
<li><a href="http://area51.stackexchange.com/proposals/22246/personal-manufacturing">Personal Manufacturing</a></li>
</ul>

<p>Would it be acceptable to extract <code>good</code>/<code>relevant</code> questions out of these beta site question dumps and post them in the 3D Printing site?</p>

If someone has a question from one of those older sites, they should go ahead and ask it. But a wholesale importing of content from elsewhere is not really a desirable way to build this site.
There is a lot of ownership and careful curation that goes with vetting the content of this site. Questions imported from elsewhere would always have that air of odd, forgotten legacy content back-dated and
anonymous
with no owners or real-time vetting at all. If someone posts another answer or asks for some followup to one of these questions, no one will receive the notification. Essentially, we would be loading this site up with a lot of questions asked and answered a long time ago without imparting any of the benefits of reputation, ownership, or experience into the community that is supposed to take care of it.
That's why we don't do it.