With these drill guides, you can add additional holes for the fixed middle shelf of IKEA Billy. That way, it will hold five rows of file folders (LEITZ® or similar).
I designed it so you can instantly see if you aligned them wrong - nothing should stick out of the sides.
Align the guide marked „back“ in the first shelfholder-holes ABOVE the existing holes for the fixed shelf. Align the „front“ guide accordingly (you should see two shelfholder-holes below the jig).
Print them in whatever material you want - I used PETG with 0.25mm layer height, 5 perimeters (drills tend to bite into the material, no matter how straight you hold the drill).
You'll need a 5mm drill and a 7,5 mm (or 5/16th) drill.
There is an instructional video on YouTube:
The author marked this model as their own original creation.