IKEA Billy bookcase anti-tip wall bracket
A low-profile bracket that ties the top of an IKEA Billy bookcase to the wall and replaces the flimsy strap or a lost original fitting. The bracket is an L of 5 mm thick PETG, 60 mm wide, with a 40 mm leg that screws down into the top panel with two 4 mm screws and a 50 mm leg that carries a 6 mm slot for a wall plug and screw. The slot allows 10 mm of adjustment so the case can sit tight against the skirting board. Ribs along the inside corner stop the L from opening under load. Print it lying on the long leg for strength across the bend.
Wall spacing behind a Billy varies with skirting, wallpaper and cable runs, so a bracket generated to your gap beats a fixed one. In SpeakCAD you give the gap and screw sizes, preview the bracket in the browser at no cost, ask for a version that hides behind a Kallax in the chat and download the STL.
Create an L-shaped anti-tip bracket 60 mm wide and 5 mm thick with a 40 mm horizontal leg having two 4.5 mm countersunk holes for screws into an IKEA Billy top panel and a 50 mm vertical leg with a 6 x 16 mm wall screw slot, plus two 3 mm ribs across the inside corner.