Art Deco Flowers
It was the only decorative element of a 1915 Dutch book but I think it’s a nice one. You could use the entire page spacer design or just use the floral element. I think they are a semi-common upright water lily pattern that was common during that time period that had a bit of an Egyptian influence.
I think the art deco flowers would also make a pretty needlepoint or embroidery element too. Or maybe use the design like a rubber stamp to create an all-over background. No matter what you decide, you can’t go wrong, because it is your design and of course it will be amazing.