3DPrinting

Smooth prusa powder coated works great.

Drying makes a gigantic difference. It only takes around an hour in the open before TPU changes significantly from any ambient moisture and become visible in the print.

If you can control the moisture to a minor degree, you can alter the mechanical properties significantly. Once you hear popping, you'll likely start blowing holes in prints, but there is a stage before this where the bubbles of gases are present but are not coalescing into the larger audible voids of escaping steam. You will see this on long prints using dried TPU filament left out in the open. There will be a much tougher start to the print that gradually degrades into a slightly softer and more flexible texture. It will likely turn slightly foam-like spongy rubbery soft for a section and then it will start popping and dropping walls with holes in the structure.

If you write down the room temperature and humidity and note the time it takes to get to this moisture property, it becomes possible to alter the flexible properties or empirical hardness of a TPU to make it behave in off label ways. This is essentially creating your own rudimentary foaming or light weight filament. It works best for vase mode or other small single wall structures. I have used this based on intuition alone. I imagine with a bit of record keeping one could control the humidity of a box to do longer prints within this state of foaming softness. I don't know of anyone using a humidifier like the ones for acoustic guitar cases or cigars in a filament box, but that would be an interesting thing to play with too.