Ok, that was fast. Thanks to “jstiltner” who wrote a comment on Thingiverse.com, I was able to solve my problem with the missing tubing to complete my filament spindle box.
jstitner on Thingiverse.com:
The HDPE tubing that is used on the makerbot looks the be the same as the “polyethylene” tubing used to connect refrigerators that have water dispensers.
I found a package with 10m LLDPE tubing in a store, selling refrigerators, washing mashines and stuff like that.
It’s a water tube (I guess some kind of spare part for a water dispenser) with an outer diameter of 6.5mm and an inner diameter of 4mm. Perfect!
Thanks again to jstiltner for the tip!
I already had drilled a hole for the filament into the side of the box:
Now that I had the actual tubing, I printed an object to attach it to the filament box:
Actually I printed two of them. On the one hand, the object prints better when printing two at the same time (the ABS has a hard time to cool down enough between layers when printing only one), on the other hand I used the second holder to mount a spring with about the same OD as the tubing on the inside of the box to flexibly guide the filament. Both parts are bolt down with one M4x20mm bolt:
The tubing (with the filament inside) then goes loosely to the top of the Makerbot. I use a guidance ring, I used before to keep the filament out of the timing belt on top of the Makerbot, to give the tubing some support on its way to the extruder:
I updated the Thingiverse.com thing with the printed parts and added the STL file for the tubing holder part.