PTFE funnel for MMU (fits RepBox)

General Info

A big ole' box for keeping your filament dry and your spools turning makes life super easy but if you need to load a filament spool into tiny PTFE tube in a high, dark area, it can be a challenge.
This is a small little funnel designed to allow easy loading of PTFE tubes of various common sizes. While the funnel is printed, the travel path for filament when properly installed will be entirely lined with PTFE tubing, keeping friction to a minimum.

Which Part?

You'll need to select the correct internal funnel part based on your PTFE tubing. As the newer MMU3 standard tubing has a 2.5mm inner diameter and a 4mm outer diameter, most people will probably just want to get 2.5mmIDx4mmOD-internal-funnel. Prior to the MMU2 and most other printers tend to use 2 mm inner diameter tubing with a 4mm outer diameter which would require the 2mmIDx4mmOD-internal-funnel part.
The external fitting part isn't necessary if you're using a RepBox, the funnels are compatible with the RepBox fittings.
The external fitting comes in sizes based on the outer diameter of the PTFE tubing, and requires a push-through connector (links below). If you're using standard Prusa tubes, the 4mmOD-external-fitting part is appropriate. If you're looking to reduce friction as much as possible, I recommend a 6mm outer-diameter / 3mm inner-diameter tube and the corresponding 6mmOD-external-fitting part (although if you're loading into a system expecting 2.5x4mm tubing (like the MMU3) you'll have to work out how to step down the tubing (I should have some step down connectors coming online “soon”).
NOTE: – the connectors required here are push-through connectors; the PTFE tubing will pass entirely through the connector. Many connectors you are familiar with and may have on hand do not allow this, but instead seat the filament within the connector. With a pass through connector you will only be worried about the “outer” (external) diameter, often delimited as “OD”

Part list:

• these are not required if you are using the RepBox and are happy with the included connectors
• I don't particularly endorse these, but they've worked for me here in the US – finding push-through connectors can be a bit tricky; double check before ordering.
• Buy only the part below (or find similar online) for your size tubing.
  • For 4mm OD tubing:
    • https://www.amazon.com/gp/product/B01IB81IHG/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 
  • For 6mm OD tubing:
    • https://www.robotdigg.com/product/755/Through-fitting-PC4-M6,-PC4-01,-PC6-M6-or-PC6-01-for-PTFE-Tubing (order the TPC4-M6 part)

Source Code:

The source code loads these part profiles from easy-to-edit INI files that can be modified. The python source shown below requires the build123d library to execute.
The source code for this part is open sourced under the MIT license and can be downloaded from: https://github.com/x0pherl/repbox-funnel