Part cooling

I'm hoping that I can actually just further direct the fan air so that I can have an open, ductless hotend. The red arrow is the expected current air direction (from feeling the output air stream) and the orange is the ideal air flow with a duct similar to a tower fan or car AC.

Filament Strategy

The Aesthetic Series

I've also considered a new solution of filaments and their order:

1. White 
   1. Also used for cleaning/purging since it's readily available and white PETG/PLA/ABS is less flexible than cleaning filament thus easier to extrude.
2. Silver / Stone
   1. Silver: A bright silver material for creating silky or metallic-looking materials like copper, gold or car paint.
   2. Stone: A white, mortar-looking material for creating rocky materials like brick, sandstone or concrete. This may need the fuzzy-skin slicer feature to make it really look like stone.
3. Black
   1. Moved to before the CMY colours so that it effects subsequent colours less during changes.
4. Yellow
5. Magenta
6. Cyan
   1. Potential CMY filaments from eSun:

7. Transparent
   1. This is also so matte or glossy materials can be created. If the other materials are glossy, this would ideally make the final filament look matte.
   2. [Edit 1 - Feb 22] However, for an alpha channel, this will have to be the first material input into the system. 
      1. I have higher expectations that this would work compared to the gloss/transparency strategy.
8. TPU Glue
   1. Ideally, this is a material that usually won't stick to the previous materials so that its absence can act as a support interface.
   2. May conflict with the glossy/matte strategy (if it's even possible), which is probably fine because any print that needs that feature is likely to be more aesthetic in nature anyway. It is a better strategy to load in both silver and stone.

Other materials not considered in the above strategy:

1. Wood - would go between Silver and Black so that different grains could be printed
2. Marble - between Silver and Black, or replaces Stone
3. Glow-In-The-Dark - between Cyan and Transparent
   1. both as only the surface will emit light and so that the transparent material can both protect the nozzle and make ghostly filament.
4. CF-PETG/CF-PLA - replaces Black but would likely be in the "engineering series"
5. Soluble - replaces TPU Glue
6. Rainbow - it'll be a disappointment if such a filament is needed on a hotend like this
7. Toothpaste
   1. probably depends on the print and the colours, but I don't even know if the toothpaste effect would even be preserved
8. Foam - Like CF filaments, it's probably something for the "engineering series"

The Engineering Series

It's understandable that an engineer won't spend £300 to mod their printer just so that they don't need a massive filament rack (likely also valued at £300+). This is why I've also thought of the engineering series strategy, which is properties based:

1. The cheap all-rounder (PLA/PETG/ASA)
2. The high temp (PBT/PC/PPS?)
   1. placed after the cheap all-rounder so that there is a chance of purging it out
3. The (very) flexible
   1. So that the flexible-to-rigid range is as wide as possible.
4. Conductive
5. Chopped fibre / stiff
   1. Most of the stiff material should be formed in a tube-like extrusion as that's where most of the stress will be concentrated.
6. High inter-layer bonding, low stiffness and UV resistant.
   1. AKA TPU Glue
7. Foam / expanding
   1. Ideally, this would actually go before most of the other materials to emulate AMTEx, but I don't think reality will be so idealistic.
8. Soluble