This is a simple print which fits one of no doubt a few thousand tissue box sizes.
To change the size, log in to your free Onshape account and change the parameters shown below. (the link to the file is at the bottom of the download page)
I printed in PLA with 0.2mm layer heights and a 0.4mm nozzle. Don't forget to download the right and left hand version. Two of the same will work just as well, they just won't look as nice!
The author marked this model as their own original creation.