We wanted something fun to add to out "Squiggle Trike" at the Red Bull Creation competition last July. We had some miscellaneous stuff like solar cells, small motors, etc. What to do ... ? A bubble maker to leave a trail of bubbles behind as the trike moves! We had a Thing-O-Matic available, courtesy of MakerBot, so I spent a little time in SketchUp, tweaked it a little, and voila! It has two different sized holes to allow for variation in the soap mixture. Hopefully one or both will work for you.
This one is easy. Load up the STL file in ReplicatorG, make sure it's flat on the x-y plane, and let 'er rip!
When it's done, you may be able to use it directly with the small pilot hole that's already there. If it's too small for whatever shaft you're going to mount it on, just use the existing hole as a guide for a larger hole that's a snug fit.