the blade space is 0.45mm in the stl because the blades I have measure between 0.30mm and 0.40mm
the hole where to insert the 4mm OD PFTE tube is 4.3wide and 4.5mm tall because the top of horizontal hole tend to compress on top while printing in most FDM 3D printers
I designed it in FreeCAD 1.0 compiled from git, the design is comfortable to grab with the hands and hold firm the tube with the thumb
I printed in ABS for greater strength but PLA or PETG would be fine too as the shape is thought for good strength against the blade (the intent is to maximize the contact surface with the blade). Nylon CF might be even a good option.
I might load a 3fm file in the future (currently it's stuff with my printer information and could make confusion), anyway I recommend to increase solid top layers to a significant amount so to have 100% infill where it is needed, or even better create a rectangle below the space for the blade and only for that rectangle change solid infill paramenter to 100%
to be precise green in the picture is my previous revision which was a bit too small,
the published pfte-holdNUcut.stl adhere both to the blade and the tube tightly right when printed
The author marked this model as their own original creation.