I had to make this as Lakeland don't offer replacements for this part that always breaks. Hopefully of use to someone, somewhere!
I printed in PLA first time around, but it soon melted and warped (those racks get pretty hot!) so next used PET-G and worked perfectly.
You'll need some build plate supports if you don't flip the model in Slicer, but can be printed on it's back if desired.
The author hasn't provided the model origin yet.