Hi, I just started this model, but when I come here for some hints, there seems to be a few different versions. Which is the original.

The original is the hand-drawn one by Ninjatoes: http://ninjatoes.wordpress.com/2003/09/05/star-trek-danube-class-runabout-rubicon/ It was redrawn and cleaned up several times by different artists, including our dear friend Paragon. Apparently the best version is a beefed-up-hyper-dyper-splendid-over-the-top-top-notch-holy-frakkin'-awesome revision by Paul McCool: http://ninjatoes.wordpress.com/2012/06/23/star-trek-deep-space-nine-rubicon-runabout-by-paul-mccool/ The latest "incarnation" is an excellent 1:200 version by Thunderchild (available here in the Resource section; it even features the roll bar!!!).

The one Im building is the large version. How would I enlarge the roll bar on the Thunderchild build to fit this size model.

GREAT! I'm looking forward to seeing it! As for the roll bar, just assemble the small version and the McCool version and do some measuring (length, width, heigth). Determine the scaling factor to make sure that it fits on the big one (dimensions of the big one / dimensions of the small one = scaling factor).

You're right, the squared-off Bussards are indeed a compromise. It was necessary given the medium, and the shape of the original part, as a flattened sphere that transitions into a rectangle. If you have a suggestion for how to achieve a more prototypical shape, I'd be happy to look at it. P. McCool

This is where forming a part with two part Epoxy, then softening some blister pack to pull over would give you excellent results, and not be very difficult. This method has been show many times on this forum.