This is a grease injector for LM8UU/LMU8 linear bearings. It fits the Nigrin 74145 multipurpose grease with a M24x3 thread on its tube. This is the grease I use for my bearings which is easy to get and quite cheap in Germany.
Support is only needed on the bottom area of the injector to support overhangs. Best use Prusa Slicers function for paint-on supports.
Inspired by the model from @jnull but remixed from the original by @uepsie.
The author remixed this model.