My bureau windows had a holder for the external blinds shaft that was broken for years.
I never took the time to change it, until today.

This holder is used to keep the shaft against the wall.
The shaft diameter is 14 mm, and this is probably pretty specific.

I have included the .sat file to this thing, which should allow you to modify it as you need.
The initial design was made in Autdesk fusion 360.