WARNING:  I have just discovered that as of 2011 this kind of drop-side crib cannot be sold.  The hardware can break and allow the child to fall between the side and the mattress.  I created clips to immobilize the side so it can't move.  See my immobilizer here:  https://www.printables.com/model/1520535-delta-crib-immobilizer-set

Original post:

Crude, but fits and works well.

We bought the crib used, and one upper track was missing.  I copied the existing track, and it worked first try.

I made without support, but if I needed another I would enable support. There were random filaments in the slots that support would have eliminated.

Printed on my Bambu A1 Mini by laying diagonally on the bed.

The photos show the original (orange) track and the printed (white) track.