Here's the parts and assembly pictures for how we make the GEK ejector-venturi.  This solution will pull to about 20" of water vac, via a 1/8" air jet.  The entire assembly is made from plumbing parts, chosen to approximate the best practice dimensions for ejector-venturis.

We integrate the ejector-venturi, mixer and swirl burner into a single "Eturi Tree".  This creates a single assembly that is easy to move from one location to another on your system.  The integral mixture valve let's you dial in your fuel/air mixture you get a perfect clean burn, as well as more easily maintain your flame with poor gas. 

The swirl burner in general gives you a much more stable flare than a linear burner, as the swirl is constantly bringing the flame back on itself.  You can also add some steel wool in the base of the swirl can for easy relighting.  Or add one of various heating element options to get auto lighting without a propane torch. Swirl burner specific building instructions are here.

Most personal scale gasifiers need a 5" or 6" swirl burner can.  We use as 5" on the standard GEK.  6" on the larger Power Pallets.

See also the wiki page on our early tests of the "Eturi Tree".