The sculpts of Bunsen & Beaker were based on the really-for-real puppets that were used in the production of "Muppets Tonight." The folks at Muppet Holding Company LLC (Now Muppet Studios LLC) made these cloth characters available to WDI. And the Imagineers then carefully measured each Muppet to make sure that they got the scale on each of these new "Living Creature Initiative" figures just right.Link (Thanks, Ricky!)
More to the point, Dave Goelz made a trip down to Glendale late last year to consult on the Muppet Mobile Lab project. And he reportedly seemed thrilled with the job that WDI had done with his character, Dr. Bunsen Honeydew.
So when will Bunsen & Beaker stop playing the party circuit and finally make an appearance in the theme parks? According to what I've heard, the Imagineers weren't entirely pleased with how the Muppet Mobile Lab performed at Disney's corporate Christmas party. Which is why this "Living Creature Initiative" unit was then taken back to Glendale for a little tweaking. (More to the point, so that the roughly-worked-out scripts for Bunsen & Beaker's mostly improv routines could be punched up a bit).