Simple sign for the Dutchies among us. I attached it to our mailbox, to politely remind the mailman to close the lid of our mailbox to minimize drafts inside our house.
I designed it to use as minimal filament as possible, approx 11 grams. The size is 17cm width x 5.2cm height but you can scale it up or down to your liking. I recommend to print it in ABS or ASA to make sure it doesn't melt from the sun.