Vitsoe 606 shelf T-nut

You need a M3 bolt + M3 threaded insert (OD 5mm, length 3mm…8mm). After printing, melt the threaded insert into the piece.

Print “upright” for best quality (I found other orientations made the nut not fit exactly). No supports needed.

Choose print material, infill and threaded insert length based on the mechanical load you plan to attach.