This is a stand based on SungiKim's version, but this one fits the bergshult IKEA shelf (20cm deep). I made this version for the 80x20x2.5cm shelf, but it would certainly fit the 120x20x2.5cm - although you might need to print an additional one to fit in the middle.
Included Sketchup file in case anyone needs to tweak it.
Pretty straightforward print - printed at 0.3mm 20% infill.
The author hasn't provided the model origin yet.