Enjoy your command of the skies! Here's another video: And another one, where it's slightly less than neutrally buoyant: ...
Step 8: Mounting Braces
Now that your blimp is working ( and hopefully you've tested it by now to make sure that it is), you need a way to attach it to your soon-to-be-inflated envelope. Cut 4 strips of balsa beam, about 2" long, and on the end of each glue a square of balsa just big enough to fit a velcro patch. Glue one of these struts to each corner of the blimp frame. They too will need some triangular supports, so cut out 16 of these - mine were right triangles, with the short legs about 1/2" long. On each strut, glue two to support the square and two to support the column at its base, as seen in the picture. Finally, press a velcro patch onto the pad of each column, and its adhesive should hold it there nicely.
You've built the 'gondola' of the blimp. Now you just have to get it airborne.