A stand for Proxxon or Dremel, with a 20mm diameter holding part.
Mounted on the plate with 4xM6 screws, 80mm between slots.
Brackets (equerre in french) are maintained with M5 hexa screws.
The pictures show the first version, STL are a little bit differents.
EDIT : added equerre v2

I printed these parts 100% infill to make them strong, but maybe less is enough ?...