This cover keeps wasps from drinking your beer before you do. 

It takes labout 2 m of 1.75 mm filament and less than 30 min to print (on my printer at 0.3 mm layer height).

The cover fits standard aluminium beverage cans with 54 mm rim outer diameter (typically 0.33 liter and upwards). If necessary you may adapt the dimensions to your can by editing the enclosed .scad source file (see instructions below) e.g. for energy drink cans (typical dimensions included in the source file).

Inspired by
https://www.thingiverse.com/thing:5438844/files
but different solution.