Derived from the design of thing 17965 by dmeehl. I haven't been able to find a good mount for my Printrbot+ LC but dmeehl's was close just not quite long enough because it was designed for a different printer. I mocked it up in Tinkercad and made it a bit longer so that it should fit my laser cut extruder.
The original design ended up not working too well in practice, it bent too much but it might work in ABS better so I will leave it on the model. For v2 I basically redesigned it from scratch to be much simpler and more stable. v2 is the one I am using on my Printrbot now and it seems to be working well.
This is designed for my Printrbot+ LC but I believe most of the Printrbots use the same or similar extruder design and this is basic enough to work with a bit of tolerance. Leave some comments if it you have a different model and let me know how this thing works.
Super basic slic3r settings printed mine well, it is designed to be simple. I used 2 shells but 3 might be easier to print the thin strip. Mine is in PLA but ABS should work just as well.
Once printed just remove the right front screw on your extruder and replace it with the mount attached using the tab at the top for stability. The gauge should mount on the other screw with a nut and a few washers. I used some extra screws that came with my bot and some of the extra washers. Standard M3 hardware should work fine, the holes on the mount are 5mm.
In this design you have to remove the gauge before you can print but if you sand the top right corner off you might be able to swing the gauge up enough to be out of the way. I might redo the model later on if that becomes something necessary.