Pretzel Can

Notable Features


The idea behind this piece was simple: make a watering can in the shape of a knot. I wanted the knot to look dignified, but with a subliminally positive feel, due to a heart shape (the heart is upside down, but it is there). Water would flow through the 'rope' from end to end. There would be no noise - nothing that could be added or subtracted.

Achieving perfect economy of form, a sense of inevitability - it could not be other than the way it is - was, as you might expect, hard. 

In trying to clear this bar, I experimented with almost every variable: rope widths, wall thicknesses, relative scaling, sweep line. Functional constraints often presented problems. But, when it comes to a tool like a watering can, functional constraints are non-negotiable. 

And there are more than you'd think. The hand must comfortably grasp the handle while carrying and also pouring; water must flow smoothly from the spout, but only when inclined at an appropriate angle; it must be easy to fill and hard to spill... 

Five prototypes were required before I was satisfied with the result, each design requiring complex manual assembly in CAD. This was due to the many self-intersecting walls, which, so far as I can tell, cannot be trimmed and welded using standard modeling tools like Grasshopper.


Hollow all the way through: a test print in progress

This difficulty may explain the dearth - the total absence perhaps - of hollow, self-intersecting surfaces in the 3D printing world.

Alas, this was but the beginning of the struggle. A key piece of creating a 3D printable part is called meshing, where the surface of the CAD model is divided into thousands of tiny triangles, which are required for the next step in the data pipeline (slicing). 

And this pretzel shape did not lend itself to meshing. At all. A series of odd hacks was required to achieve a smooth mesh. Nor did the shape lend itself to slicing. Eight print tests were required before I found a combination of settings that achieved a smooth outer surface.

User testing revealed that home gardeners loved its clean lines, plus the laminar flow of the pour. Fascinatingly, we all really misjudged the volume of the can, which is a hefty 500 ml, or 1 1/2 soda cans worth.

My final step is figuring out how to print the can in the more practical PETG plastic and the more luxurious porcelain. 

V1 completed November, 2021