I started making Vroid textures recently and I was using someone else’s automatically centered symmetry tool a lot, but found myself needing a guide ruler in the center too, usually to cut a symmetrical image in half. That’s why I really needed it to be a guide ruler specifically, so that I could set my tools to snap to it.
Turns out, it’s easier to make a layer template of a ruler that automatically goes to the center of a canvas than I thought, so I did it. Just drag it to the canvas and it’ll go to the center. Easy!
Of course, it won’t adjust with your canvas if you change the dimensions, but if you delete the ruler folder and then re-add it after you’ve changed your canvas dimensions, it’ll be in the center again.
This layer template contains:
-1 horizontal guide ruler
-1 vertical guide ruler
-1 vertical symmetry ruler (2-sided)
-1 blank raster layer
Each ruler is on its own layer, so you can turn each one on or off as needed.
Troubleshooting:
It should be pretty straightforward, but some things may need to be explained regardless.
If you’re having trouble with the rulers, make sure that the ‘Enable snapping’ box is ticked in your Sub Tool Details. If it’s not visible in the Tool Property palette, click the wrench in the lower right of the Tool Property palette and click the Correction category. You’ll have to make sure this is ticked on any sub tool you want to use with the rulers.



Also, if you have version 4 of CSP, you can turn on ‘Snap To’ for even more snappy alignment goodness:

Hope this helps someone else out there! Enjoy!