I really liked laurentine's design for a gothic-style flying buttress bookend. I was looking for something to prop up my Hellboy books when I came across her post on wordpress and thought this was absolutely the right way to present my collection. Liking her design very much, I recreated it in Tinkercad. I scaled down to be able to print on my Prusa Mini, but will include the larger scale version if someone wants to print and glue it together to make a larger version.
 

I printed this in PETG, but would probably look cleaner and more presentable if printed with PLA. I used 20% infill, but its really up to you since its only a bookend and only needs to be sturdy enough to prop up books. If printing the scaled down version, you should be able to print without supports if your printer is properly tuned except maybe the two arrow shaped posts.