i. This model provides a dust cover for the holes around the z-axis rods, but will still allow the linear bearings to go through them and bottom out properly. When they do, you will need to reinstall the covers, as they are made to move out of the way and become dislodged. But as long as you don't bottom out the z axis, they should stay in place and prevent dust, filament, screws, etc from falling down in the holes. 

This is better than the original model I uploaded, which shortens build height by 25mm. These don't shorten build height at all. 

I would recommend printing with a 0.4mm nozzle and a fairly low layer height (.12 or .16), merely because the model is so thin and small; however, I test printed it in PETG with a 0.6mm nozzle at 0.18 layer height and it printed just fine by reducing the line width. The version I'm using in my own Centauri Carbon is printed in TPU

ii. Differences of the remix compared to the original

This is based on the volcano shaped guide rod dust cover that was brilliantly created and published by @JesseZhang for the X1C. I reduced the overall size to fit the smaller z-axis guide rod hole of the Elegoo Centauri Carbon and made the brim a little wider for stability.