Keep your security deposit and save a bunch on buying ones off the shelf, since these little puppies sit in windows all day the plastic becomes brittle and prone to cracking with age. Currently for me at least they're almost impossible to buy in stores and I'm not a big fan of waiting for delivery so I knocked up these bad boys one Sunday afternoon. I've included the standard sizes that were sold at my local hardware store and also included my FreeCAD file so you can make any size that suits you if need be, simply change the length in the size spreadsheet and the model will automatically update.

Recommended Material:

PLA for colder climates

PETG/ABS for warmer climates

Print Settings:

0.2mm layer heights

3 perimeters

3 skin layers (top bottoms)

20% infill

ramp up the print speed for everything except you initial layers to save some time since you're really not going to ever see them