Many printers, especially those with a Bowden extruder, use PC4-M10 fittings to retain the PTFE tube at the extruder. Reportedly on Bowden printers it helps with retraction if the fittings at both ends have a firm grip on the PTFE tube so that it can't move during a retract. I saw a couple of clips that were designed to hold the fitting retainer up which helps firm up the tube retention. However, neither of them really fit the PC4-M10 fittings that are commonly available here in the US. So I designed this clip.
I tested the clip on a couple of different brands of PC4-M10 fittings, and it worked well on both. It's possible your fittings have slightly different dimensions, so I've included the Fusion 360 file for the design. Ping me in the comments if you're not able to use that to make any needed changes on your own.
I printed with 2 perimeters, 100% infill. I also had "Detect thin walls" enabled. I recommend using a filament with a little flex to it, such as PETG.