I have a step-by-step how-to i just did i’d love to share here. I’m a new user on this forum, so it won’t let me post pictures (kinda the point for folks like me who are visual). I’ll post it up here as soon as i get rights to link images in my posts.
It’s pretty easy and only takes a few hours if you take your time doing it. Quality of the 3d print will really make a difference, but even a rough print is a huge improvement over the large GT2B’s stock size!
Oh yeah, xcode won’t know how to handle an stl file. You can easily download Cura (free 3d printing software made for the Ultimaker, but works on others as well and can be used as a viewer) or a site like this if you want to look at it in 3d, and they will often gives some type of measurement.