Pencil Case with Ruler

I needed a pencil case for work, where I also need a short straight-edge which has to include some circle templates. Rather than using and carrying a separate straight-edge/ruler, I've combined them into the removable lid.

Files created & exported using Shapr3d on my iPad. Sliced in PrusaSlicer. This printed really well in PLA (although with my default Prusa PLA settings, it took over 24 hours). 

Any feedback would be appreciated - keeping in mind this is my very first design (I'm new to CAD and I'm trying to learn Shapr3d) and this is only the third or fourth thing I've printed with my printed.