It's a bong designed to look like a bolt.

I designed it to print with minimal print artifacts, to be compatible with common grommet and downstem sizes. The design is interesting and has been approved by serious stoners for use. I've even sold the finished product to people for $20 (that's an $19 profit when you factor in electricity and plastic [provided that the downstem and 18mm grommet are not included with sale]).

The extension is not necessary but is recommended to give it the classic bong appearance, prevent splashing from a big hit, and provide space for more ice to be held by the ice-pinch. 

The bong was designed to print in a 200mm x 200mm x 180mm build volume.