IKEA and PAX are simply used to describe the products these are supposed to be used in conjunction with and have no relationship with this product.
The boards, Komplement, for PAX in 50x58 have been sold out and unavailable at my ikea for a while now. So I just bought a random board in the Fundgrube and cut it to size. The holes to hold it in place of course do not line up, and they aren't that important, as long as most of your boards have them. So I removed the peg that goes into the board, since I was too lazy to dril holes in the board, especially since they should only go up to a certain depth. At least for me it works perfectly like this.
Printed mine out of PETG at 13% Infill, 2 Perimeters. Fit perfectly tightly for me as is.
Print on side, with supports on build plate.
The author remixed this model.