Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:3941427.

Made this thing to put a Google Home Mini on my old Staples shelf system ("ClosetMaid Shelftrack Elite Bookshelf Kit"). Kind of flimsy due to the small size, but it was a quick design/print. Of course, this is intended for the old Google Home Mini and not the new Nest Mini that can already be wall-mounted.

The slots for the shelf are approximately 18.91 mm x 3.25 mm and spaced 6.91 mm apart, so maybe it will fit other shelf systems.

Edit 10/31/19: added a stronger version that is only one piece.