I noticed that the lid of my Sunlu S1 box would sometimes open while feeding the filament through the top hole, especially when using an adapter with a PTFE tube attached to it. I made this wedge to stop that from happening. Just make sure you remove it before opening the lid to replace the filament. ;-)
Make sure you print it in a tougher material like PETG with 20-25% infill. When installing it, make sure to push it all the way down and use the orientation in the second picture so pressure is created on the lid by the wedge.
The author marked this model as their own original creation.