Sharpie, USB and SD Card Holder

I made this “organisier” to get familiar with Onshape as Shapr3D started charging waaaay too much for what it was offering. 

This model took several hours to print, and could do with some optimisation. Also the model in the photos is not quite the same as the one in the 3d file - sharpies don't have a uniform diameter, they're actually skinnier at the bottom. The new file has the sharpie holes at 11.5mm instead of 12.5mm. It should hold the pens a bit more firmly, but if people want the original I can upload that too.