My preferred weapon for 3D modelling is OpenSCAD, so that will be my choice to recreate the part.

Luckily for me, I still had all the pieces of the broken part available with a little epoxy leftover which won't hinder my reverse-engineering.

The part in question is rather simple from a geometric standpoint, so I started by getting my trusted calliper out and measuring everything I could : thickness (uneven though the part), diameters and other dimensions. The only thing I couldn't get with my calliper was the angles between the two mains beam of the part (at least without resorting to trigonometry).

I then took some photos of the part, as flat as I could, then loaded the file into Photoshop (I'm an amateur photographer) and used it's Information panel  to get the angle from the photo (61°).

With all this information I launched OpenSCAD and tried to replicate all the important parts of the geometry (it's not a complete replica, but the usefull fetures are here).

At my fourth iteration the part fit perfectly, but I felt that the grip on the glue stick could be improved. I added some small tooth on the contact layer with the glue stick and voilà, my final replacement part was born.

Nothing special on the printing part : 0.3mm layer PLA

It still works today, more than 3 month after my fix.

2018-01-28 EDIT : I added the finished part photo, and also a photo of the part in use.