Gridfinity Ruler Holder

Remix of https://social.thangs.com/m/74621

A 1x1x6 sized block for storing rulers and other flat things. The difference between mine and the one I remixed is that this one can be stacked onto.

An extension of #GridFinity, open sourced by Zach Freedman: https://www.youtube.com/watch?v=ra_9zU-mnl8