This is a derivative of the model from the Manga/Book Riser for IKEA Billy shelves (https://makerworld.com/en/models/31671#profileId-28234).

I have altered the dimensions so that you can fit two of these side-by-side on the Ikea Billy bookcases, with more height to see more of the books that will sit on top of them.

Although they are meant to be hidden away they should fit fine on most shelves.

Dimensions are:

X - 180mm

Y - 125mm

Z - 120mm