Ikea Billy repair part

The last generation of Ikea Billy bookshelf seem to be not very solid. My ones crashed some days before. The sidewalls buckled, and the boards came down and stacked at the bottom. This weakness is caused by the badly designed connection between the horizontal boards and the vertical sidewalls. In order to fix this, I designed this little repair part. Now, one can fix the connection with 3 screws. The middle hole in the row of three is for a 5 mm pin which is available in tool shops and which used to be the connectors in ancient Billy´s. With this 5 mm pin, one gets the new part exactly in the right height. I made this hole in Tinkercad at 5 mm which is a bit too tight for the 4,9 mm pin, so I re-drilled the hole after printing at exact 5 mm which worked fine.