Centering Registration Marks

[tamihowse]

Does anyone know how to center the registration marks without doing a lot of math?
For instance, I have a large design which is a word collage. I'd like to center a registration mark on each side, centered vertically as well as horizontally. I have made my own in SCAL, lined up with my image, but if there's a simpler way, I'd love to hear about it. I've looked all over and can't find anything.
Fondly, Tami

[Louise-paisley]

Its easy in inkscape, not so easy in SCAL as it does not have much in the way of alignment tools..

if you group all your cuts..

Now create your reg mark for left and right, roughly the correct distance apart, select them and the grouped cuts and align vertical, create the top/ bottom marks and select them and the grouped cuts, align horizontal..

Gets you close to what I think you are attempting