I created this series of minimalist bird feeders. Each of these uses suction cups to attach to your windows, and ¼" wooden dowel rods that you can cut down for a perch. 

This model contains a sun-shaped circular design, but each of these bird feeders contain the following design features: 

• Wooden Dowel perch (the original design didn't have this, but my wife said “Where do the birds stand?”) - The dowels I used are ¼" x 12" (6.4mm x 305mm) I purchased from Amazon. They will need to be cut to length.
• Custom designed dowel clips to prevent the birbs from stealing your dowels.
• Suction cup attachment points - I used these suction cups, but the important bit is the 6x19mm bolt. 
• Removable seed basket for easy refilling
• A rain hood to help mitigate rain and also to add safety from predatory birds.
• Stylish raindrop drain mounts to prevent water collection and seed rot.

Recommended Print Settings

• PETG is recommended for weather and UV resistance. Mine are mostly shaded, and so have been printed in PLA. 
• All parts are oriented for maximal printability without AMS
• The circular trays do require supports, and supports are configured in their print profiles - Detachment should be easy, but you know your printer better than I do, so adjust as you like

Bill of Materials

(because some people won't read the above)

• Heavy Duty Suction Cups
• 1/4" x 12" Wooden Dowel Rods