I bet it&#x27;s only &quot;well understood&quot; by a very small group of people in 2015.<p>On the other hand, at least it&#x27;s _possible_ to make your own at home: <a href="http:&#x2F;&#x2F;makezine.com&#x2F;2008&#x2F;01&#x2F;07&#x2F;make-your-own-vacuum-tube&#x2F;" rel="nofollow">http:&#x2F;&#x2F;makezine.com&#x2F;2008&#x2F;01&#x2F;07&#x2F;make-your-own-vacuum-tube&#x2F;</a><p>I somehow doubt there&#x27;s many talented amateurs assembling MOSFETs in their garages...