This lid is designed to fit a 90mm PVC pipe stingless bee feeder.It can be used in conjunction with the feeder float file when the total height of the feeder is less than the length of the float. In this instance, the hole in the lid works to right the float, acts as an alternate access point for bees and the stem of the float acts as a liquid feed level indicator.The hole in the lid is 20mm and the diameter of the stem on the float is 15mm. In my observations with Tetragonula Hockingsi, this gap allows for access by the bees but excludes larger insects.You may wish to alter the hole diameter depending on your preference, what species you are feeding and the tollerance of your printer.The float can also be used in a larger/longer feeder without the need for this lid.

Please note that the photos above also show an earlier prototype where the hole and stem are much more slender. I found that this stem was prone to breakage, but have maintained the same crawl space in the new design. (Blue lidded feeder)

Please consider the environment when 3D printing.