Print in the orientation as downloaded, support-free. It just slips on top of a tissue box for an elegant decoration and to keep the box in place when pulling a tissue. 

It should fit any square tissue box that is within the dimensions of 5.25in x 5.25in x 5.25in (about 130mm in each dimension). From what I can tell this should be suitable for all standard square tissue boxes, but I'm happy to adjust if anyone needs it!

I used Protopasta's Matte Olive Wood Fiber PLA. Mine weighs about 250g, which is a good chunk of plastic but it is totally worth it. Let me know how your turns out!