This is my version of a DIY ant moat for a hummingbird feeder. I looked them up, and those question-mark-shaped screws are called either 'crown bolts' or 'cup hooks'. Very cheap at a hardware store or Target, etc. ...
by Lan Anh Handmade
by shreyash craft
by Crafting Guys
by Potomac Bead Company
by Ras Art Creations
by Crafts And Kutir
by knits and bits